StarTuned Magazine June 2014

Who's Your Partner in Success? Mercedes-Benz's f!) PartsPro

You've chosen your career as an ISP

(Independent Serv ice Prov ider) because you enjoy mainta ining, diagnosing, and repa iring

motor vehicles. One of the most challenging

pieces of your business is parts procurement.

Find ing the right parts at the right price and

being certain they w ill arri ve when promised

can be a challenge.

Wouldn't it be nice if there were a way to

get the par ts you need w ithout the hassle

and uncer ta inty, so you can get back to the

important business of actually fi x ing cars and

tak ing care of your customers?

With the Mercedes-Benz PartsPro wholesale certi Fi cation prog ram, now there is!

Pa rtsPro is a rigorous program intended

to t rain Mercedes-Benz dealership pa rts

departments on how to better take care

of you and ultimately your customers.

Par tsPro certified dea lers have elevated their commitment to supporting the independent repair channel, and w i ll prov ide you wi th the

highest level of customer ser v ice. They focus

on the things that matter most to you!

CONVENIENCE ... AccuRACY ... PROFITABILITY . . . DELIVERY

A PartsPro dealer has the tools in place to better meet the needs of their es teemed wholesale customers.

For a dea lership to achieve Par tsPro

Certificat ion, parts department person nel must

first undergo intensive "customer-cent ric"

2 Mercedes-Benz StarTuned

t raining which teaches person nel how to better help YOU.

There's far more to PartsPro than just

customer-serv ice tra ini ng. The dealership must

make specific comm itments to provide "Best in

Class" ser v ice in areas such as logistics, which

includes ISP-focused parts ava i labil ity, regular

deliver y serv ice, outs ide sa les people to prov ide you personal ized serv ice, as we l l as a dedicated

phone line and "w ill ca ll " pick up area.

THEN THERE'S TECHNICAL HELP. On occasion we all need a helping hand. Your

Pa rtsPro dealer is there to assist. Whether it mea ns prov iding, diagnostic ass ista nce, information on suppl ies or special too ls, or

anything else you may need to assist you in repa iring your customers' Mercedes-Benz

vehicles and get them back on the road as fast

as poss ible.

Only those dealerships that meet the stringent cert ification requ irements earn the r ight to

display the "PartsPro" logo. Additionall y, t hey

receive ongoing consul tation and tra in ing to

ensure that they are consistently provid ing the

very best suppor t to you, the ISP customer.

We hope you are already receiv ing indust ry lead ing serv ice from your Mercedes-Benz dealer; however, once PartsPro Cert i fied, we believe you' ll be thri lled w ith the new "Best in

Class" parts-procu rement experience!

Of course, you'll cont inue to have the

peace of mind that i nstalling only Genuine Mercedes-Benz par ts can prov ide. I

..

TO OUR READERS:

Welcome to STARTUNED, the magazine for independent service technicians working on Mercedes-Benz vehicles. Your MercedesBenz dealer sponsors STARTUNED and provides the information coming your way in eaoh issue. Mercedes-Benz wants to present the information you need to know to diagnose and repair Mercedes-Benz vehicles accurately, quickly and the first time; text, graphics, on-line and other technical sources combine to make this possible. Feature articles, derived from approved company sources, focus on being useful and interesting. Our digest of technical information can help you solve unanticipated problems quickly and expertly. We want STARTUNED to be both helpful and informative, so please let us know just what kinds of features and other diagnostic services you'd like to see in it. We'll continue to bring you selected service bulletins from Mercedes-Benz and articles covering the different systems on these vehicles.

Send your suggestions, questions or comments to us at: STARTUNED One Mercedes Drive Montvale, New Jersey 07645 Phone: 1 201.263.7284 E-mail: [email protected]

STARTUNED is a publication of Mercedes-Benz USA, LLC ("MBUSA"). No part of this magazine may be reproduced without the express written permission of MBUSA. Editorial and Circulation Offices: 1348 River Road, Montague, NJ 07827. CAUTION: Vehicle servicing performed by untrained persons could result in serious injury to those persons or others. Information contained in this magazine is Intended for use by trained, professional auto repair technicians ONLY. This information is provided to inform these technicians of conditions which may occur in some vehicles or to provide information which could assist them in proper servicing of these vehicles. Property trained technicians have the equipment, tools, safety instru:tions, and know-how to perform repairs correctly and safety. If a condition is described, DO NOT assume that a topic covered in these pages automatically applies to your vehicle or that your vehicle has that condition. STARTUNED is a registered trademart of MBUSA.

Group Publisher Christopher M. Ayers, Jr. [email protected]

Contributing Editors Bob Chabot [email protected]

Kerry Jonnson [email protected]

Michael Klaas [email protected]

Tom Nash [email protected]

Frank Walker [email protected]

Editorial Director Bob Freudenberger [email protected]

Technical Advisor Tim Amun

MBUSA Technical Content Advisor Donald Rotolo [email protected]

MBUSA Project Manager Stefanie Schweigler [email protected]

Art Director & Circulation Mgr. Christopher M. Ayers Ill [email protected]

Visit us at our web site www.MBWholesaleParts.com to view this issue and past

issues of StarTuned, along with a wealth of information on Genuine Mercedes-Benz Parts.

To locate a Mercedes-Benz dealer near you, go to www.mbusa.com.

IN THIS Issue

4 WHY You SHOULD Use ONLY GENUINE MERCEDES-BENZ PARTS

There's a lot more substance to this topic than you might think - it's not just marketing hype. The rigorous "Genuine Parts" testing program is especially interesting and relevant to the price/ value relationship.

12 MODERN MOTOR MOUNTS

Mercedes-Benz has always been an innovator in the automotive industry, and its powertrain technology shows this clearly. But besides the great leaps in engines that have produced the wonderful performance and efficiency of today, has anybody ever given any thought to how those engines are mounted in the chassis? Yes, indeed, and to a larger extent than you probably suspect.

20 MOST DEFINITELY, FROM D2B

The addition of electronics has turned the average vehicle into a technological marvel, but a Mercedes-Benz is no average vehicle. At the cutting edge of technology since its founding, the company has added fiber optics that allow it to process large amounts of digital media. What do we need to know if it stops doing that?

28 BUMPER TECH

The safety sensors are embedded in or attached to the bumper and front grille, which makes bumper repair after a collision very different from the procedures of only a decade ago.

Why You Should Use Only Genuine Mercedes-Benz Parts

There's a lot more substance to this topic than you might think - it's not just marketing hype. The rigorous "Genuine Parts" testing program is especially interesting and relevant to the price/value relationship.


Fuel pumps need to be j ust right, or there 's potential for noise.

I n the last issue of StarTuned, we talked about why you should use only genuine

Mercedes-Benz brake parts from your loca l dealer in your service work, and we bel ieve the reasons we gave were pretty compelling.

We found the subject so interesting and important that we decided to do an addit ional article to explore the parts situation in

Mark Boege, a New Jersey ISP, tells StarTuned that he's always satisfied with Genuine Mercedes-Benz parts.

general, and the rationale behind you, the ISP (Independent Service Provider), stay ing w ith genuine M-B O.E. components. Much of this has to do with the company's commendable U.S. parts-testing programs.

In the previous article, we mentioned how genuine Mercedes-Benz brake parts were the best th ings to use because they were engineered and tailored for the characteristics

of the speci fie model invo lved, not just generica l ly one-size-fits-all. It turns out that that's the case with most of the parts you buy from your loca l M-B dealer.

OBVIOUSLY, SEEING THE ROAD CLEARLY IS IMPORTANT TO SAFETY

Take windsh ield w ipers, for example. With Genuine M-B parts, their cu rve matches that of the w indscreen of each model, so the pressure on the blade/glass interface is opt imi zed. Whi le compet ing w iper blades are made of poured rubber, Genuine M-B blades are extruded, which g ives better performance and a 20% lower wear rate -- they' re tested for 1.5M cycles! They also have a helpful wear indicator that changes

When sourced from Mercedes-Benz, big assemblies, such as this 7G-TRONIC transmission ...

June 2014 5

.. or this remanufactured engine have the industry's strictest quality control, and carry unequalled warranties. They're also often the subject of aggressive price-cutting programs.

color when replacement is needed, which

amounts to a g reat sales too l. Instal lation is far easier and faster, too, without all the confusion

of the various attachment parts of aftermarket

versions. If you look at it over the course of

a year, thi s can add up to hundreds of dollars

worth of labor.

Or, how about fi lters? With cabin air filters, the time required for installation also adds up. Genuine Mercedes-Benz cabin filters can

be installed more quick ly because they don't

have to be modi fied to make them fit. Seal ing is optim ized, as well. The seal is tested for blow-by w ith special equipment that measures particles in the air.

Air filters are tested for 2,000 miles over the

same route. The tests have proved that the use


The cost of replacement engine management computers (PCMs for Powertrain Control Modules, to use SAE's standardized terminology) is another thing on which Mercedes-Benz has instituted money-saving programs.

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·-The EPC (Electronic Parts Catalog) is sophisticated and comprehensive. You'll always get the right part the first time. It's free, too. Just visit http:/l__epc.startekinfo.com.

of genuine air fi lters has a substantial impact

on fuel efficiency. Especial ly w ith diesels,

performance also goes down when a nongenuine part is installed.

INDEPENDENT TESTING IN THE U.S.A. We've mentioned tes t ing, but the Mercedes

Benz Genuine Parts Testing Program is much

more comprehensive and appropr iate to ou r

market than you probabl y know. The test ing

is designed to measure the actual impact the quality of the par t has on the customer. In other word s, for rea l-world situat ions, not for

some ivor y-tower idea.

Tes ting is done in the U.S., which assures

that the findings are rea lly market-appropr iate.

Not only does Mercedes-Benz se l l more vehicles in this country than anywhere else, the U.S. also has special conditions (there's

nothing in Europe equal to Death Val ley),

differen t fuel blends, bigger

engines, and un ique regulations.

Th is is true road testing; it 's not done on a dynamometer.

The locat ion with in the U.S. is chosen according to the type of

part being tested. For example,

testi ng brake pads in the bruta l

stop-and-go traffic of Los Angeles

is idea l. Both genu ine O.E. and aftermarket l inings are installed

on vehicles that a re cl r iven on a predefined route for one month.

The driver has a "cl icker," which

he or she can hit during a brak ing

event that exhibits issues such

If you've been in the auto service business for any leng th of time, you 've seen problems with the quality of aftermarket remanufactured alternators. This is never an issue with Genuine Mercedes-Benz parts.

as noise or vibration so that the on-board equipment records it . Microphones are used for brake noise, and brake dust is measured with a photometer. Even something

as subjective as pedal feel is eva luated. Once again, testing is

for impact on the customer.

June 2014 7

Who conducts a\\ this disciplined testing?

In ever y case, Mercedes-Benz employs

independent laboratories to be sure the resu Its

are from an objective third party and are not

skewed by brand loya lt y.

CONVENIENCE, SPEED, AND ACCURACY MBUSA offers a powerfu l tool that can

streamline your parts-sourci ng research

efforts: The EPC (Electronic Parts Catalog),

a comprehensive and easy-to-use parts look-

up system. It's a big help and t ime-saver in

searching for exactly the right part, assu ring

that you'll always get the correct thing the

first time (which is often not the case in the

aftermarket). This w ill go a long way toward

avoiding the schedu l ing disasters that can make

customers unhappy with you. The download

is free -- visit http:/Jepc.startel<i nfo.com. We

believe you' ll actually enjoy using it.

Something that's not often mentioned is the

problem you may have finding a specific part

for an older model -- Mercedes-Benz owners

typica lly keep their vehicles for a long, long

time, so it's likely that you' ll often have cars

in you bays that almost qual i fy as vintage, or

even classic. You can waste a lot of time and

end up frustrated searching for parts for these

venerable vehicles from the aftermarket, whereas

the EPC covers them in detai l, and inventories are scrupulously maintained even for what are

sometimes ca lled "heri tage automobiles" (they

may very well be used as daily drivers).

There's more to electronic parts sourcing aids.

MBUSA has launched the new www.mbwholesa leparts.com. Among its useful

features are model designation charts and

technical information resources that will help you

order the right parts and make installations easier.

Those electron ic aids combined w ith the

superior quality, competitive pricing, and

excellent warranty protection you get when you make the commendable dec ision to purchase


genu ine Mercedes-Benz parts wi ll contribute to your peace of mind and reputation.

PRICE/VALUE Over the years, we've seen various carmakers

overcharge for their O.E. parts to an egregious extent,

trusting that obedient motorists or shop owners

wou ldn't question the amount. One example that we

especially remember was a sensor for one upscale

make that the dealers charged over five times more

for than the same Robert Bosch part number could

be bought elsewhere.

That's not the kind of high-handed pricing

pol icy Mercedes-Benz fol lows. The company

does a yearly evaluat ion to make sure its

Genuine Mercedes-Benz replacement batteries are made by the best European manufacturers.

Basic aftermarket catalytic converters that barely meet EPA guidelines are notorious for having short lives. This genuine replacement unit will last as long as the original.

¥:co\tr Workshop Resource to Get the Job Done • WIS-net (Workshop Information • Maintenance Sheets

System}

• Wiring Diagrams

• Technical Bulletins

• Mercedes-Benz Special Tools

• Star Diagnosis System (SDS)

• Mercedes-Benz Workshop Equipment

@ Mercedes-Benz

prices are competitive. lt's often found that certain parts, fue l filters for instance, are

more expensive from aftermarket suppliers.

And there's never an issue w ith quality, fit, or

warrant y protection when you go genuine.

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~"' .. ~ --·--·--With today's strict guidelines for antifreeze, is there ever a reason to use anything but the exact O.E. formula?

I t can be difficult to find parts for an older model, such as this Klima relay, from aftermarket sources. Searching for them takes your valuable time when you could simply go genuine and have easy sourcing from Mercedes-Benz.


As Kerry Jonnson, one of our es teemed

technica l contri butors to StarTuned, has

stated, "In the automotive repa ir business, our

customers rely on us to prov ide the type of

serv ice that allows them worry-free operation

of their vehicles. They don't understand how

complex these vehicles have become. They

just know they need their vehicles to operate in a safe and pred ictable manner. Here is

one buy ing decision you can make that will

help you achieve thi s goa l." That mea ns

"partnering" w ith your local Mercedes-Benz

dealer 's pa rts depar tment.

We' ll conclude w ith a statement from another Mercedes-Benz expert: "Say you have a customer

who's spent lots of money to buy a nice E-Class.

Using non-genuine parts wou ld be li ke replacing

a link in a chain w ith a paper clip. It impacts the

entire performance leve l of the car." I

It's not only parts, but also tools and equipment. Where else can you get something like this comprehensive electrical connection kit but from your local Mercedes-Benz dealer?

It seems to be in the genes

of Mercedes-Benz engineers

to cont i nuously look for any

possible way to improve the

company's veh icles. Every aspect

of those vehicles is thoroughly

evaluated and an incredible

amount of thought goes into

every component, both ex isting

and yet to come. Even something

as simple as a door handle is

studied and improvements are

made. Most people don't g ive

much thought to door handles, but

Mercedes-Benz has engineered a

stronger one so that i n the event

of an accident you can get a good

grip and open the door even if

it has been damaged. This may

seem like a small improvement,

but we're sure first responders

appreciate th is simple feature.

This is how Mercedes-Benz

approaches everything that its

vehicles are composed of. Over

the years, all ki nds of dramatic

technologica l advancements

have been introduced into

the automotive i ndustry, and

Mercedes-Benz has typica lly been

a leader in th is.

Tn recent decades, the world of

personal transportation has gone

through such rapid evolut ion

that perhaps "revolution" is a

more accurate word. As high

technology has taken over, serv ice technicians have seen

more clearly than ever before

the need to keep pace w ith it.

Modern electronics started with

fuel inject ion, ign ition, and

feedback engine management

sys tems to control emissions

and increase fuel economy. The

electronics revolution con tinued

with ant i-lock brake systems

(ABS), then t raction control and

the Electronic Stability Program

(ESP). Mercedes-Benz was one of

the fi rst manufac turers that, in

conjunction w ith Robert Bosch

A.G., developed CAN (Controller

Area Networks). Th is led the

way for indiv idual computerized

systems to become integrated

and work with each other to

form systems like ESP. A ll th is

computer ization, of course, adds

a certai n level of complex ity to

our jobs w hen something goes

wrong. It's our responsibi lity as

technicians to lea rn continuously

so we can prov ide competent

diagnosis and ser v ice to our

customers. There are some

components, however, that you

probably never wou Id associate

w ith electronic controls -- motor

mounts, fo r exa mple.

PROACTIVE There is a debate in th is country

over whether the automotive

i ndustr y has suffered more

from government bu reaucracy

forc ing unnecessary change, or

from the market forcing more

socia lly-responsible developments.

Regard less, Mercedes-Benz

has responded admirably to

these challenges. One of its major initiati ves has been the

development of diesel engines that

g ive luxury vehicles levels of fuel

efficiency prev iously achieved

only by sub-compacts, along with

astonishing performance and low

em iss ions. Those attributes still

wouldn' t sway the American consumer, however, if NVH (Noise, Vibration, Harshness) hadn't

been reduced al most to the levels of a gasoline

burners. One of the factors in the success of that

effort was the invention of an entirely new type

of motor mount.

Through most of automotive history, motor

mounts have been mundane. In early cars, they were simpl y brackets, bolts, and nuts

that held the engine rigidly to the chass is. Of course, that meant that all the v ibrations,

jerks, and shocks that originated w ith i nternal

combustion were transferred directl y to

the unfortunate dri ver and passengers. It wasn't long before mit igating that motoring

unpleasantness became a priority. The first, and longest-running, attempt at accomplish ing

this reduct ion in v ibration was the adoption

of mounts that incorporated rubber isolators

to absorb part of the unwanted harshness any

rec iprocating assembly transmits. Sta rting in the

earl y 1930s, thi s idea was

reasonably successfu l, if not ideal.

Much more could be

done to isolate the delicate

occupants of a vehicle

from internal combust ion's basic brutality. So, Mercedes-Benz eng ineers

developed motor mounts

that did just that.

Most of the company's vehicles currently on the road have hyd rau I ic

engine mounts that

Engine mount design: 1. Flange 7. Hub 2. Seal bellows 8. Retaining ring 3. Diaphragm 9. Cover 4. Check ball 10. Bore 5. Buffer stop 11. Solenoid 6. Protective cap

go beyond the simple idea of using rubber's

compressibili ty to reduce

roughness -- oi I is the medium used to dampen the v ibration a running

The two-wire harness is a surefire give-away that this is a computercontrolled mount. It is powered up by fuse F58. If you unplug the fuse and plug it back in with the key on, you should hear the mounts click.


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With a paid subscription to www.startekinfo.com you can access wiring diagrams. Here, you can see that components Y123 and Y123/1 are the switchable engine mounts. They're wired together so both mounts get grounded at the same time by the ME.

Ml (Fuel pump)

M4n (Combustion engine and air conditioning with Integrated control

fan motor) M16/6 (Throttle valve actuator)

M55 (Intake port shutoff actuator

a motor) Ulll R39/1 (Vent line heating e lement)

• R4B (Coolant thermostat heating

l!!!I element •!- -II Y77/1 (Boost pressure postt loner)

YB5 (Exhaust gas recirculation cooler bypass SWltchover valve) Y2719 (Exhaust gas recirculation actuator) Diagnostic glowing

Injector shuto!T

Status of associated actual value

Name Actual value Spacllledl4•• Switchable engine mounts Fault. 53336/6058

I:> Actuate components ·y123 (Len switchable engine mount)' and 'Y123/1 (Right switchable engine

mount)'.

Terminate actuation.

If you have made the investment in Xentry, you have the ability to bi-directionally control outputs. One of these is the switchable engine mounts.

June 2014 15

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engine generates. Somewhat similar

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... ENGINE 642 In MODEL 166 of a suspension

shock absorber, the oi I is forced th rough an ori fice

between two

chambers at the top and bottom of

the mount as they

are compressed and expanded

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by engine shake.

When these fa i l,

it's from a loss

of fluid, and

typica lly causes

a more sudden

These modern motor mounts are still serviced in the same way as a conventional unit with the minor exception that there is an electrical connector to unplug. With your paid subscription to www.startekinfo.com, you can access WIS and get a step-by-step procedure for diagnosing and replacing the new mounts.

and pronounced clunking than you'd get from a graduallydissolv ing rubber mount. Diagnosis is mostl y

a matter of observation. l s the bottom chamber fl at? Is there oi l present?

Speaking of the work ing fluid, whenever

you're try ing to track down an oil leak, say

from a cam or t iming chain cover, don't overl ook the possibility that the rea l culprit is a ruptured motor mount. We should also ment ion

that some aftermarket parts suppliers subst itute

ordinary rubber mounts for the hydrau l ic type,

wh ich is another reason you should stick w ith

Genuine Mercedes-Benz parts.

COMPUTER CONTROL? While hydraulic motor mounts work qu ite

well, they're still passive. They have no ability

to adapt to the differi ng cond itions encountered

as engine modes change. Since transforming

the public perception of the characteristics of diesel-powered cars is turning out to be a lengthy process, Mercedes-Benz has been doing everyth ing possible to reach that goal. Not

only with sophisticated common-rai l injection


with multiple events and ingenious aftertreatment of the ex haust, but also by givi ng an unsung and overlooked part a fresh look:

the lowly motor mount. In order to endow its

diesels w ith a smoothness that r iva ls that of a

gasoline eng ine, Mercedes-Benz has developed computer-controlled mou nts.

These new "e lectri c" or "switchable" engine mounts were introduced in 2011 on the

Mercedes-Benz M-Class w ith the 642 diesel

(166 Chassis). Instead of hyd raulic oil , they

use air conta ined in three bel lows. An internal

electri ca l solenoid valve either connects the air chambers together, offering a large vo lume of air for the compression and ex pansion that

absorbs v ibrations, or closes off the chambers from one another for a firmer mounting (the default position is the "hard" setti ng w ith the

chambers isolated).

Two w i res run from the harness to the solenoid, one 12V, and the other ground, which is controlled by the ME (Motor Elec tronics). Even with sophisticated common-rai l injec tion, diesels can be rough during cran king and

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Here we are looking at the activation of the switchable engine mounts with the Xentry software. Notice how the ME simply grounds the solenoids in the upper trace. The lower trace shows the amperage draw of a single engine mount.

start ing, and tend to shudder when shut down. So, the ME is programmed to activate

the solenoid during these modes, making a relatively-large volume of air avai lable to absorb any harshness. This is ca lled the "soft" sett ing.

The solenoid is either energi zed or off, there's

no in-between.

XENTRY AND DMM Although you may not be seei ng these mounts

for years, you shou Id sti 11 know how to diagnose them. I f you've invested in Xentry software, you

can ac t ivate the solenoid at w i l l and monitor both the amp draw and the computer's ability

to control the ground side of the circu it. You

can also use your DMM (Digital Multi-Meter)

to check the resistance of the solenoid and look for an open windi ng. You should read about 27

ohms with a good solenoid.

The power feed is fu se F58. This fuse also

supplies the diesel fuel injection system solenoids, the pressure regulating va lve, and

the quantity control va lve. So, a short circuit

or any other fai lure that causes the fu se to blow wi ll cause a no-start cond ition, and the mounts

wi ll default to "hard," which won't be noticed

with the engine stopped. These mounts may be

incorporated into other models in the future, so be sure to check the w iring diagra ms for the car at hand by v isiting StarTek lnfo.com.

Remova l and replacement is basica l ly the

same as with any other engine mount. There

are two fasteners that hold it to the engine sub-frame, and a sing le fastener to the engine mounting bracket. The only add itional step is

unplugging the elect rica l connector.

As we sa id earl ier, with modern technology

being appl ied to more and more aspects of automobiles, it is your responsibil ity as an

ISP (Independent Ser vice Provider) to keep pace with these changes and continue your education. This allows you to keep giving your

customers what they expect from you. It 's also in your own best financial interests. I

Ju ne 2014 17

er ormance.

uccess. With our competitively priced Genuine Remanufactured Parts, you no longer have to settle for anything less than Mercedes-Benz quality. But that's just part of the story. You see, our airmatic struts, catalytic convertors, turbochargers and steering racks all carry a 1 2-month, no mileage-restriction warranty. So our parts are not only a great deal. They're a great value. And since they're genuine Mercedes-Benz, you can have confidence they'll last, and so will your relationship with your customers.

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A 164 460 0300 80

Mercedes-Benz

MOST Definitely, from D2B The addition of electronics has turned the average vehicle into a technological marvel, but a Mercedes-Benz is no average vehicle. At the cutting edge of technology since its founding, the company has added fiber optics that allow it to process large amounts of digital media. What do we need to know if it stops doing that?

One of the first steps in diagnosing a problem with the MOST bus system is to establish communication with the MOST master control unit. In this case, it is the COMA ND ® radio. Verify communication first. If you do not have communications, check the fuses, power, and ground to the control unit. If you have communication, you can move on to the next step.


We've all seen electron ics take hold of ou r

industry. It started with electronic ign ition

(mandated in 1975), then fuel injection, and now

seemingly every component on the car is either

contro lled or monitored by electronics. This

generall y makes systems more complicated. There

are sensor inputs, a processor, and computer

controlled outputs. While this added complexity

can make your life more difficult when something

breaks, it can also make it easier.

SDS XENTRY software is designed to interpret

the data of the processors and can retrieve

diagnostic trouble codes, g ive you rea l-time data,

and also allow you to bi-directionally control

computer outputs so you can find out if the

components receiving commands are actually

working. Having this in formation allows you

to quickly look at data you may find useful in

diagnosing the problem. Once you isolate where

the trouble is, you can then do more specific

electrical test ing to verify your conclusions.

You'd feel pretty si lly if you spent hours doing

high-tech diagnosis on ly to find out that an

electrica l connector was not plugged in properl y.

GETTING THE MOST Nowhere is thi s technology more evident

than in the entertainment system. These have

different needs from body control or powertra in

systems. Powertrain systems need high-speed

data transfer because t rac tion control , engine

management, and suspension features need

to work together to keep the car under control

during spirited drivi ng. Body control systems

ca n operate at a much slower speed and the

vehicle's occupants won't notice the difference.

Entertainment systems do not need high speed,

but there is a whole lot of in formation that needs

to be moved around --visual and audio media

files are large. This in format ion must be sent

from the d igital med ia reader (CD/ DVD player),

the display screen, and the sound system. If

these systems transferred information across

electrica l lines the w iring involved would have

to be ver y complex. For thi s and other reasons,

Mercedes-Benz has chosen to use fiber optics for

transferring digital media.

Fiber-optic systems offer many advantages

over conventional elect rica l wiring. Number

With a paid subscription to www.startekinfo.com, you can pull up a chassis-specific wiring diagram. You can compare the wiring to the MOST bus list of control modules and locate each component. Notice that the Orange lines are wired in series. This is the fiber-optic line. The purple wire is the electrical "Star" wiring electrical bus the MOST master uses to see which control units are waking up and which are not.

one, they are capable of carry ing large amounts of data very qu ick ly. Number two, fiber-opti c

systems send I ight messages along a cable, so

they're not subject to magnetic inter ference, or

RF!. They do requ ire a discrete fiber-optic l ine

routed with the w iring harness, which does acid a level of complex ity. Fiber-optic cable is fa irly

sturdy, however, and is not subject to corrosion from water intrusion as elec trical wiring is.

The main ru le for routing fiber-opti c cable is simply not to bend it enough to crimp it.

Usuall y, you don't have to worry about the cable un less accident damage has compromised it. I n

that event, replace it.

MASTER Mercedes-Benz started its adopt ion of fiber

opti cs with the D2B (Domest ic Digital Bus)

system, which was developed exclusive ly by the company. The net work is routed in seri es -- there

is one fiber-optic cable coming in and another coming out. In order fo r this system to work,

"someone" has to be in charge, so every D2B

system has a "master." This is the one control

unit that is in charge of all the others. Th is is

important to know because th is is the con trol

unit you are talking to when you communicate

w ith it using the XENTRY diagnosti c software. Since the fiber-optic network is routed in ser ies, it is important for the codi ng of the

master control un it to not only k now al l of the

components on the fiber-optic r ing, but also the

order in which they are connected. Not every

D2 B system is the same --someone may have ordered a car w ith or w ithout a mu ltiple-disc CD changer, for example.

Another thi ng that's important to know about

a series-wound fi ber-optic system is that i f one

component fa i ls it can bring down the whole

system. Nothing w i ll work. You may th ink it would be a big undertaking to diagnose a whole system that is not working, but it is rea l ly not that di fficu It. The Fi rs t th ing you need to

es tablish is communicat ion with the master


Locate the first component on the fiber-optic bus and unplug the connection to that unit . When you turn on the ignition key, you should see one of the cables light up with the fiber-optic signal as shown here. Plug i t back in and move on to the next control unit until y ou no longer see the cable light up. This means either the cable is bad, or the control unit before it is not putting out a fiberoptic signal.

control unit. In the case of the D2B system,

the master is the COMAND® control unit -- the

interface mounted in the center of the dash. Use

your XENTRY software, or eq uiva lent, to try to

establish communication w ith the master. I f you do have communication, then you can assess

li ve data about the other control units on the

028, pu 11 diagnost ic troub le codes that may lead

you to the problem, or "p ing" the control units

on the D2B bus and see what answers back.

STARTING POINT If you do not have commun ication w ith the

master COMAND® un it, that's the first thing

you must fi x. Start with check ing power,

ground, and the wake-up signal to the control

unit. Remember, if the master is not functioning

then nothing else wi ll , ei ther. The first thing

you should check are the fu ses that power up the master COMAND® unit. I f the fu ses

have power, the nex t step would be to pu l l the COMAND® unit out and veri fy the power and

ground supply to it -- check for damaged or corroded w iring. lf you have power and ground,

then you may want to put a lab scope on the CA lines to the COMAND® unit and ver ify

that the scan tool communicat ion signal is

making it to the module. I f every thing is there, then you may simply have a bad COMAND®

unit. Mercedes-Benz offers remanu fac tu red

uni ts through you r Mercedes-Benz dea ler's pa rts depar tment.

I f you have commun ication with the

COMA ND® unit, t hen the diagnosis is even

easier. If the system is down, it has probably set a diagnostic trouble code in the COMAND®

unit. This wi l l probably lead you to the trouble, but even if it doesn't there is testing you can

per form to isolate the problem. From the master

COMAND® un it, you ca n cal l up the cod ing for

the unit and you w i l l k now what opt ions are installed in the vehic le you are work ing on.

This is a big help in diagnosi ng the fiber-optic system. What you ca n do at thi s poin t is access

the first contro l uni t the fi ber-opt ic signal is sent to and unplug the cable from that cont rol un it. Turn the ign ition l<ey on and obser ve the

If you purchase a fiber-optic loop, you can bypass a possibly bad control unit. If the system starts to work, you'll know the control unit is the problem. Before replacing the control unit, verify that it has the proper power supply feed, ground, and wake-up signal.

June 2014 23

cable plug. You should see one of the cables blinking. This is the optica l wake-up signal

from the master.

THE NEXT STEP

If you see the blinking light, you know the master is putting out the optical wake-up signal. You can then plug the connector back in and move on to the next control unit on the

fi ber-optic bus. Unplug that connector, turn the ignition key back on, and watch for the same bl inks. Keep moving on through the next cont rol units until you no longer observe the bl inking. Remember, the Fiber-optic net work is in series. So, the control unit that you just unplugged is not the one you're testing. You're look ing for the output signal from the control unit before it's on the bus. If you no longer see the wake-up call, it is either not coming out of the control unit before it's in the network, or the cable has a break in it.

You can purchase a special fiber-optic loop tool, which is sort of li ke a jumper w ire. You can plug it into the fiber-optic connector of each control unit

the fiber-optic network with an electrical

wake-up line. This signal is generated by the master control unit, but it is conventionally wired in parallel. The wake-up signal is sent and each control unit answers on this wakeup line. The control unit that does not respond has fa iled. This is how the master control unit senses the system fai lure and sets diagnosti c

trouble codes. Veri fy power and ground and you have diagnosed the problem.

EVOLUTION, NOT REVOLUTION The only rea l difference between the D2B

bus and the next evolutionary stage, the

MOST (Media Oriented System Transport), is the communication protoco l. The diagnosis is exactly the same. Use XENTRY to compare the elec trica l wake-up signal and compare it to the fiber-optic network. The two special tools for the D2B and MOST sys tem are inexpensive and available from your local Mercedes-Benz dealer's part department -- remember, they 're

happy to help. I

on the network. If you turn the key on and the system starts to work, then the control unit you just bypassed is

. Transport Screvv Rernova l Advice

the problem. This does not mean the control unit is necessaril y bad. You sti 11 need to verify power, g rounds, and the wake-up signal at that control unit, starting with the fuses that power it up.

Mercedes-Benz has made diagnosis even easier by backing up


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The MOST bus is programmable with XENTRY software. Remember, if you want to add a component to the MOST bus you need to go into the MOST master and change the coding for the new configuration. You must get the order right in the fiber-optic loop for stable MOST bus operation.

Mercedes-Benz Mobil 1 Product Name Part Number Quantity Product Description Recommended Consumer Applications

MercedeirBenz SPEC.

BQ 1090144 Bulk - No Equipment Mobil 1 BQ 1090162 6/1 Quart Cases

Fully synthetic formulas designed Low SPAsh. Available at most MB dealers Formula M 5W-40 specifically for gasoline passenger cars

BQ 1090151 55 Gallon Drum

Genuine A0009898301 USB6 12x1 Quart Cases · Mercedes-Benz Oil Fully Synthetic formula specifically . . MB 229 .5 A0009898301 USBB 55 Gallon Drum designed for Mercedes-Benz engines Mercedes-B.e.nz Engines that require Specification that require the 229.5 Specifica tion 229·5 Specification Oil SAE 5W-40 A0009898301 USB9 Bulk - No Equipment

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Mobil 1 ESP BQ 1090135 Bulk - No Equipment Formula M 5W-40 Advanced full synthetic formulas designed specifically for diesel Low SPAsh. Available at most MB dealers

BO 1 09 0142 6/1 Quart Cases passenger cars that have particulate

BQ 1 09 0143 55 Gallon Drum filters

Higher viscosity, advanced full synthetic

BQ 1 09 0134 6/1 Quart Cases formula designed for performance Porsche A40. HT /HS applications. vehicles

Extra high performance automatic Recommended tor use in Mercedes-Benz BO 1 09 0166 55 Gallon Drum transmission fluid formulated with selected HVI base oils automatic gearboxes

Advanced full synthetic formulas Low SPAsh. Available at most BQ 1 09 0165 12x1 Liter Cases designed specifically for passenger car MB dealers. diesels that have particulate filters

1 AdBlue• 1/2 Gal. A 000 583 0107 1 /2 Gallon Bottle Non-toxic solution that transforms Recommended for use in Mercedes-harmful Nitrogen Oxide (NOx) emissions Diesel Exhaust Fluid BQ 1470002 55 Gallon Drum from diesel-powered vehicles into Benz, Volkswagen + BMW AdBlue• (DEF)

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BQ 1090017 6/1 Quart Cases Advanced full synthetic formulation designed to meet the requirements Vehicles that require 5W-30. Corvette

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Mobil 1 lOW-30 BQ 1090020 16 Gallon Keg Advanced full synthetic formula designed for domestics and imports Vehicles that require 5W-30 or lOW-30


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Eords Cbr>!slers aad aewer Iaimtas BO 1 09 0169 6/1 Quart Cases Advanced full synthetic formulation Most vehicles that specify OW-20 (newer

Mobil 1 OW-20 AFE designed for enhanced fuel economy Toyotas and Hondas), 5W-20 and certain BQ 1 09 0168 55 Gallon Drum and cold weather performance hybrids

Mobil 1 OW-30 AFE BQ 1090174 6I1 Quart Cases Advanced full synthetic formulation Most vehicles that specify 5W-30 or designed for enhanced fuel economy and cold weather performance lOW-30

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Mobil 1 15W-50 BQ 1090023 55 Gallon Drum Boosted, higher viscosity, advanced HT /HS applications. Racing and Flat full synthetic formula designed for performance vehicles tappet applications

Mobil 1 Gear Oil Exceeds the most severe service SUITABLE for use in modern high

(Mobil 1 Gear Lube BO 1 09 0085 12/1 Quart Cases requirements in both conventional and performance automobiles like SUV's,

75W-90) limited slip applications Vans and Light duty trucks requiring API GL-5 level performance

M ercedes-Benz automobiles are designed to perform on

the most challenging roads and conditions. Shouldn't the oil

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That's why Mercedes-Benz and Mobil 1 have partnered to

offer an unbeatable combination of total engine performance

and driving luxury.

Please have a look at our oil portfolio which is available

through your local Mercedes-Benz dealer. Our dealers are able

to offer you a wide variety of oil grades at competit ive prices.

Product Name Part Number Quan tit Product Descri tlon Mercedes·Benz SPEC.

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BO 1 09 002464 Bulk - No Equipment Formulated from quality base stocks

BO 1090171 12/1 Quart Cases combined with modern performance

Mobil Special 5W-30 additives to give the engine the expected

BO 1 09 003064 55 Gallon Drum protection and performance under a wide variety of operating conditions

BO l 09 003164 Bulk - No Equipment Formulated from quality base stocks


Mobil Special lOW-30 additives to give the engine the expected



BO 1090173 12/ 1 Quart Cases combined with modern performance

Mobil Special lOW-40 additives to give the engine the expected




Mobil Special 5W-20 additives to give the engine the expected


Formulated from quality base stocks combined with modern performance

Mobil Special 20W-50 BO 1 09 004664 55 Gallon Drum additives to give the engine the expected protection and performance under a wide variety of operating conditions

BO 1090053 Bulk - No Equipment Extra high performance diesel engine

BO 1 09 0058 12/ 1 Quart Cases oils that help extend engine life in

Mobil Oelvac 1300 the most severe on and off-highway Super 15W40 BO l 09 0059 4 / l Gallon Cases applications while delivering outstanding

performance in modern, high-output, BO 1090060 55 Gallon Drum low-emission engines including those

with Exhaust Gas Recirculation (EGR)

Mobil Delvac 1300 and Aftertreatment Systems with Diesel

Super 10W30 BO 1090086 Bulk - No Equipment Particulate Filters (DPFs) and Diesel Oxidation Catalysts (OOCs)

BO 1 09 0051 4 / 1 Gallon Cases Fully synthetic supreme performance heavy duty diesel engine oil that helps

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BO 1090052 55 Gallon Orum drain capability and fuel economy for modern diesel engines operating in severe applications

BO 1 09 0078 60/14 oz Cartridge

BO 1090079 120 lb Keg Formulated to provide excellent high

Mobil Grease temperature performance with superb XHP 222 BO 1090080 400 lb Drum adhesion, structural stability and

resistance to water contamination BO 1090098 40/ 14 oz Cartridge

BO 1090096 120 lb Keg Extra high performance. automotive Mobil Lube HD lubricant formulated from select base Plus BOW90 BO 1 09 0097 400 lb Orum oils and an advanced additive system

specifically for limited-slip differentials

Recommended Consumer Applications

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Recommended for gasoline fueled automobiles and light duty trucks requiring an API SN/SM/SL/SJ


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Specifically recommended for the latest low-emissions, high performance diesel applications equipped with aftertreatment systems using Diesel Particulate Filter (DPF) and Diesel Oxidation Catalyst (DOC) technologies

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Recommended for industrial and marine applications, chassis components and farm equipment

Recommended for use in limited-slip differentials, axles, and final drives requiring APl GL-5 level performance

Bumper Tech Mercedes-Benz Safety Systems Help Avoid Accidents and Significantly Change Bumper Repair

Mercedes-Benz safety technology features state-ofthe-art sensors that constantly monitor the position of the vehicle relative to other vehicles and obstacles. Software analyzes sensor data and, if necessary, sends commands to various safety systems to alert the driver to a potential problem. If the driver does not respond quickly, the system can pre-pressurize the brake master cylinder, reduce speed, or stop the vehicle, apply the brakes in a manner that prevents an unsafe lane change, or backing into an alreadyoccupied space, and adjust seat belts, seat position, head rests, and other supplemental restraint components in preparation for a possible collision. All of this is made possible by short- and longrange radar and other sensor technologies. The safety sensors are embedded in or attached to the bumper and front grille, which makes bumper repair after a collision very different from the procedures of only a decade ago.

There are six Parktronic sensors in the front bumper of this 2010 GL 450. The small round sensor heads blend beautifully into the bumper, and enable several different safety functions, including adaptive cruise control, lane departure warning, and other collision avoidance systems.


Mercedes-Benz safety technology features

state-of-the-art sensors that constantl y monitor

the posit ion of the vehicle relati ve to other vehicles and obstacles. Software analyzes

sensor data and, i f necessar y, sends commands

to various safety systems to alert the driver to a potential problem. I f the driver does not

respond quick ly, the system can pre-pressu ri ze

the brake master cy linder, reduce speed, or

stop the vehicle, apply the brakes in a man ner that prevents an unsafe lane change, or backing into an already-occupied space, and

adjust seat belts, seat position, head rests,

and other supplemental restraint components

in preparat ion for a possible collision. A ll of

this is made poss ible by short- and long-range

radar and other sensor technologies. The safety

sensors are embedded in or attached to the

bumper and front gri lle, which makes bumper

repair after a col lision ver y different from the procedures of on ly a decade ago.

Automotive sa fety st rategies have historica lly

been passive in nature. Seatbelts, ai rbags,

bumpers, and other devices sought simpl y to

reduce the impac t of a collision on the vehicle and its passengers. Over the past 15 years or

so, however, new safet y technologies have been

developed that emphasize acc ident avoidance,

and in more active ways than could be imagined

on ly a few decades ago. Much of th is new safety tech no logy features h igh-tech sensors that see th rough the Mercedes-Benz front and rear

bumpers, so bumper repair is no longer a simple straighten, patch, and re-pain t job.

For example, ordinary cruise control keeps

driv ing speed at a pre-set pace, but Adapt ive

Cruise Control helps maintain the desired distance between the vehicle and the one immediately ahead. This function is enabled by

the Mercedes-Benz Distronic Plus system.

Distronic Plus features a combi nation of

short-range radar sensors beh ind the bumper

cover and a long-range sensor in the front

gri I le. These sensors together measure the distance between vehicles, and al low the

electronic logic to determ ine whether or not

that gap is decreasing. The software assesses

how quickly the gap is decreasing and

determines how much braking power is needed

to restore the gap to the preferred length. The

system then progressively applies the brakes to slow the vehicle and restore the gap to the desired distance.

There are four Parktronic sensors in the rear bumper of this 2010 GL 450. Parktronic sensors in the rear help with lane departure warning and Parking Assist functions. There are similar sensors in the front bumper on many Mercedes-Benz models.

A vehicle traveling at 50 k mh (31 mph)

covers 20 m (65 ft.) in two seconds. Adaptive Cru ise Control aler ts the dr iver to a dangerous situation v ia flashing lights in the dash or Head

Up Display, but does not wait for him or her to

take action. Mercedes-Benz Distronic Plus radar

technology is never vu lnerable to the things

that somet imes distract humans from the road

ahead, and it responds faster and w ith more

precise application of braking force than any dri ver could, no matter how sk illed.

Mercedes-Benz Pre-Sa fe Brake is another

example of active safet y st rategy. Pre-Sa fe

Brake sensors scan the road ahead for potential

problems. If they detect a vehicle a head

slowing, stopped, or crossing its path, or "see" pedestrians or other obstacle, the system alerts

the dri ver.

Pre-Safe Brake simultaneously initiates up

to 40% of the available braking power. When

the driver brakes, the appropriate amount of braking pressure is instantly applied, all the way up to 100% if the driver so chooses. And

should the driver fa il to respond, the system will apply full braking on its own, to help

avoid or reduce the intensity of a coll ision.

Independent studies show that th is precharg ing of the brakes shaves enough off of the

driver 's reac tion ti me to effective ly increase

the occupant survival rate in an accident by 10 to 15%.

This abili ty to take control of vehicle brak ing

is only part of the Mercedes-Benz act ive sa fety

strategy. Pre-Safe also adjusts vehicle restra int systems w ithi n mil liseconds, to prepare for

a potent ial acc ident. Tt tightens the front seat

belts, adjusts the front head restrai nts and

passenger seat, and, i f the vehicle is equ ipped

w ith the Mercedes-Benz Memory System, can

even close the w indows and sun roof.

HIGH-TECH BUMPER CARE Suppose a customer comes in w ith the

complaint that after a minor front collision, the

Adapti ve Crui se Control no longer works. You'll

need to add to your t raditional coll ision-repair

knowledge in order to help this motorist.

Mounted in the front bumper cover on vehicles eq uipped with the Parktronic system are six u ltrasonic sensors. They can not

Collision avoidance sensors sit behind plastic grille covers in each side of the front bumper of this 2014 ML 350.


>

be repaired. If one has been impacted in a

collision, it must be replaced. Even if on ly a few scratches penetrate the paint and dig in to the

sensor surface, complete replacement of the

sensor is required.

If the repair i nvolved replacement of the

Distronic (DTR) control un it, the sensors that monitor rotationa l speed, yaw rate, and latera l

acceleration, or of the steering column tube module, the DTR control unit must be initialized

and recalibrated.

Another possible cause of problems w ith

the shor t-range radar sensors is the seal ing

ring where the sensor seats into the bumper.

The sensors and con nec tors are designed to be waterproof, and to resist a high degree

of v ibration and shock. If the sea ling ring is

damaged, it may al low vibration or moisture to

overwhelm the sensor. A damaged seali ng r ing

should be replaced.

PAINTING BUMPERS Have you had a customer bring in a vehicle

w ith the complaint that after another shop

repai red a bumper, the backup assist,

lane depar tu re warning, or other collision

avoidance system no longer works? It could be the paint job.

When painting the bumpers, it is important

to ensure that the paint coat on the short-range

radar sensors is of only minimal thickness.

Too thick a coat can lead to malfunctions

because the sensors see it as an obstacle in the vehic le's path, rather than as merely excessive paint thickness. The system will respond by

either keeping the warning lights or beepers

constantly on, or shutting down completely after

a certain amount of t ime to prevent full-time

appl ication of the brakes and activation of key elements of the supplemental restraint system.

The maximum paint thickness allowed at

the sensors is the primer and two coats of

paint (color and clear). Primer, color, and clear

together count as one refi nish, but the painter

MUST be mind fu I of keeping each coat as

minimal as possible.

We shou Id mention that pre-painted sensors

are avai lable for cer ta in popular colors.

When it detects an obstacle (like the two-by-four stud we placed in front of this vehicle), the Parktronic system begins flashing red lights in two places on the dashboard.

June 2014 31

The scuffing over the Parktronic sensor in the rear bumper of this 2010 GL 450 is enough to require sensor replacement.

PLASTIC: REPAIR OR REPLACE? Damage to bumper covers and protective

bumper strips in the form of cracks, holes, and scuff marks deeper than one millimeter can be fi xed using the Teroson plastics repair k it (see the approved materials I ist at

http://porta l.aftersa les.i.dai m !er.com in the

paint technology guidelines sect ion).

The Teroson k it includes a cleaner that removes dirt, grease, and other contam inants, a

primer that prepares the surface fo r fi ller, a t wo

part adhesive filler, and a glass fi ber mesh. The filler hardens in 15 minutes under an in frared

lamp. The fi ber mesh rei nforces the adhesive to

help resist repair fa ilure due to expansion and

contraction of the plastic over ti me.

With six sensors in the front and four in the rear bumper, it is easy for filler that is feathered out from the damaged spot to overlap one or more sensors. The add it ion of primer, basecoat,

and clearcoat can then quick ly build up to levels in excess of paint thickness max imums, renderi ng the affected sensors inoperable. If the damaged area is close enough so that the fi ller would overlap the sensor, replace rather than repair the bumper.


Mercedes-Benz short-range ultrasonic Parktronic sensors insert directly into the back of the plastic bumper, and include a seal that helps them resist road-induced vibration and shock.

BUMPER BASICS A MJrcedes-Benz bumper consists of three

or four basic components: a decorative plastic

bumper cover, a foam impact absorber bar, a steel or alu minum reinforcement bar, and, depending

on the vehicle model, outer protective strips.

The foam impact absorber bar is located

between the decorative cover and the metal reinforcement. Its purpose is to compress and

absorb some of the damage in a low-impact

col lision. Be careful when handl ing the foam

inserts, as they snap easi ly.

The metal reinforcement bar attaches to the

front crossmember and is designed to absorb some of the energy of a low-impact collision.

In a two or three mile per hour "parking lot"

incident, the damage to the vehicle may be

limited to the bumper cover, impact absorber, and reinforcement bar.

The Mercedes-Benz reinforcement bar

is a si ngle-use component, and ca nnot be

repa ired. If it has been damaged, it must

be rep laced.

Some models feature outer protective

str ips. A lthough primari ly decorative,

t hey are sacrificial plast ic p ieces. They are inexpensive and snap on using c li ps, so they are easil y replaceable i n the event of

mi nor impact or scratch damage.

BOLT-ON MODULES Front and rear modu Jes absorb and deflect

some of the impact energy of a col I is ion

away from va luable mechan ical components.

The modu les bolt on to the upper and lower longitudinal members (frame rai ls). The

bolt-on design helps reduce repair ti me and

cost ver sus a welded fu 11 frame.

An aluminum reinforcement bar is built onto the crossmember of the front module. A foam impact absorber sits between the decorative bumper cover and the reinforcement bar.

June 2014 33

ADDITIONAL CONNECTORS IN MERCEDES-BENZ FRONT BUMPERS

• Washer Flu id Reservoir - On vehicles

w ith a Headlamp Washer System, you

must detach the electrica l and fluid

hose connections from the windshield

washer fluid level indicator switch and

pump, and remove the Washer Flu id

Reser voir in order to access and replace

the front bumper.

• The Outside Temperature Sensor - clips to

the front bumper, and must be disconnected

in order to remove the bumper.

THE FEW, THE PROUD, THE KNOWLEDGEABLE

These new safety features a re based on

cutting-edge sensor technology and are now

being seen for the first time by many coll ision

repair technicians. Di g into your Mercedes-Benz

train ing in formation and learn how the systems

work. You'll find that k nowing where a sensor

is located, how it must be posit ioned to "see" so

it can accurately esti mate the vehicle's position

relative to nearby objects, and how your repair

prep and painti ng procedures must adjust to

avoid in terference w ith sensor operat ion w i ll

make you an in-demand ex pert in your market. I

The Mercedes-Benz front module bolts onto the upper and lower frame rails. In a low impact (up to eight mph) accident, the front module may absorb all of the collision energy as it crumples, leaving the frame rails undamaged. In that scenario, repair involves simply bolting on a new front module.


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Enjoy easy access to technical information and resources. At STAR Teklnfo you'll find all the technica l documentation you need on servicing and repai ring Mercedes-Benz veh icles.

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StarTuned Magazine June 2014

Automotive

Transcript of StarTuned Magazine June 2014