1. GeneralA: GENERAL DESCRIPTIONI The on-board diagnostics (OBD) system detectsand indicates a fault in various inputs and outputsof the complex electronic control. CHECK ENGINEmalfunction indicator lamp (MIL) in the combina-tion meter indicates occurrence of a fault ortrouble.I Further, against such a failure or sensors asmay disable the drive, the fail-safe function is pro-vided to ensure the minimal driveability.I The OBD system incorporated with the vehicleswithin this engine family complies with Section1968.1, California Code of Regulations (OBD-IIregulation). The OBD system monitors the compo-nents and the system malfunction listed in EngineSection which affects on emissions.I When the system decides that a malfunctionoccurs, MIL illuminates. At the same time of theMIL illumination or blinking, a diagnostic troublecode (DTC) and a freeze frame engine conditionsare stored into on-board computer.I The OBD system stores freeze frame enginecondition data (engine load, engine coolanttemperature, fuel trim, engine speed and vehiclespeed, etc.) into on-board computer when itdetects a malfunction first.I If the OBD system detects the various malfunc-tions including the fault of fuel trim or misfire, theOBD system first stores freeze frame engine con-ditions about the fuel trim or misfire.I When the malfunction does not occur again forthree consecutive driving cycles, MIL is turned off,but DTC remains at on-board computer.I The OBD-II system is capable of communicationwith a general scan tool (OBD-II general scan tool)formed by ISO 9141 CARB.I The OBD-II diagnostics procedure is differentfrom the usual diagnostics procedure. Whentroubleshooting OBD-II vehicles, connect SubaruSelect Monitor or the OBD-II general scan tool tothe vehicle.

B: ENGINE1. ENGINE AND EMISSION CONTROLSYSTEMI The Multipoint Fuel Injection (MFI) system is asystem that supplies the optimum air-fuel mixture

to the engine for all the various operating condi-tions through the use of the latest electronic tech-nology.With this system fuel, which is pressurized at aconstant pressure, is injected into the intake airpassage of the cylinder head. The injection quan-tity of fuel is controlled by an intermittent injectionsystem where the electro-magnetic injection valve(fuel injector) opens only for a short period of time,depending on the quantity of air required for onecycle of operation. In actual operation, the injectionquantity is determined by the duration of an elec-tric pulse applied to the fuel injector and this per-mits simple, yet highly precise metering of the fuel.I Further, all the operating conditions of theengine are converted into electric signals, and thisresults in additional features of the system, such aslarge improved adaptability, easier addition of com-pensating element, etc.The MFI system also has the following features:

I Reduced emission of harmful exhaust gases.I Reduced in fuel consumption.I Increased engine output.I Superior acceleration and deceleration.I Superior startability and warm-up perfor-mance in cold weather since compensation ismade for coolant and intake air temperature.

C: AUTOMATIC TRANSMISSION1. ELECTRONIC-HYDRAULIC CONTROLSYSTEMThe electronic-hydraulic control system consists ofvarious sensors and switches, a transmission con-trol module (TCM) and the hydraulic controllerincluding solenoid valves. The system controls thetransmission proper including shift control, lock-upcontrol, overrunning clutch control, line pressurecontrol and shift timing control. It also controls theAWD transfer clutch. In other words, the systemdetects various operating conditions from variousinput signals and sends output signals to shift sole-noids 1, 2 and low clutch timing solenoid and 2-4brake timing solenoid, line pressure duty solenoid,lock-up duty solenoid, transfer duty solenoid and2-4 brake duty solenoid (a total of eight solenoids).

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2-7 [T1A0] DIAGNOSTICS1. General