Engine Controls - Self-Diagnostics - 2.2L & 2.5L: Diagnosis Subaru Forester SF рестайлинг

ON-BOARD DIAGNOSTICS

Engine Control Module (ECM) monitors engine operation and contains a self-diagnostic system which stores Diagnostic Trouble Codes (DTCs) and complies with On-Board Diagnostics Generation II (OBD-II) standards.

Self-diagnostic system is used to provide vehicle with an on-board diagnostic system which is capable of continuously monitoring efficiency of emission control system, and improving diagnosis and repair when system failures occur.

Federal Test Procedure (FTP) sets maximum allowable emission standards. Malfunction Indicator Light (MIL) must illuminate if a system or component either fails or deteriorates to a point where the vehicle emissions could increase to more than 1 1/2 times FTP standards.

If malfunction does not recur in 3 ignition cycles, MIL goes off, but DTCs remain recorded in ECM memory. DTCs may only be retrieved using an On-Board Diagnostic-II (OBD-II) scan tool that complies with SAE standard J-1978 or Subaru Select Monitor connected to Data Link Connector (DLC). Scan tool also provides freeze-frame data and can be used to clear codes.

MALFUNCTION INDICATOR LIGHT (MIL) INSPECTION

Note. The MIL, also referred to as Check Engine light, is a warning light on the instrument cluster.

DIAGNOSTIC PROCEDURE

Diagnosis of computerized engine control system should be performed in the following order

1. Ensure all engine systems not related to computer system are operating properly. DO NOT proceed with testing unless all other problems have been repaired. Basic diagnostic procedure must be performed before using specific DTC testing procedure. See «BASIC DIAGNOSTIC PROCEDURE»(ref-11745-S33755862182000112700000) .
2. If DTCs were displayed, determine whether codes are hard or intermittent. Hard codes will cause MIL to illuminate continuously while engine is running. See «HARD FAILURES»(ref-11745-S38657668232000112700000) and «INTERMITTENT FAILURES»(ref-11745-S19141747692000112700000) . For diagnosing hard codes, proceed to appropriate DTC test. See «DIAGNOSTIC TESTS»(ref-11745-S14920230722000112700000) . For diagnosing intermittent codes, see TROUBLE SHOOTING - NO CODES article.
3. If no DTCs are present and a driveability problem exists, refer to SYMPTOMS in TROUBLE SHOOTING - NO CODES article. Doing so will help identify proper system or component to check in SYSTEM & COMPONENT TESTING article.
4. After necessary repairs are made, clear DTCs, and perform verification of repair to ensure DTC does not reset.

BASIC DIAGNOSTIC PROCEDURE

Note. Subaru Select Monitor (SSM) or OBD-II generic scan tool must be used to perform basic diagnostic procedure. Follow scan tool manufacturer's instructions for proper operation. Communication with vehicle's on-board computer is through the OBD-II Data Link Connector (DLC). (Scheme 9)and (Scheme 10).

After performing procedures in PRELIMINARY INSPECTION & ADJUSTMENTS, BASIC FUEL SYSTEM CHECKS and BASIC IGNITION SYSTEM CHECKS in BASIC DIAGNOSTIC PROCEDURES article, this is the starting point for utilizing the self-diagnostic system for determining computer-related problems. After performing necessary tests as described in the basic diagnostic procedure, if no codes are indicated and driveability problems still exist, see MALFUNCTION INDICATOR LIGHT DIAGNOSIS in TROUBLE SHOOTING - NO CODES article. Scan tool functions consist of

1. MODE $01 Current powertrain diagnostic data.
2. MODE $02 Powertrain freeze frame data.
3. MODE $03 Emission-related powertrain DTCs.
4. MODE $04 Clear/reset emission-related diagnostic information.

Scheme 9

Scheme 10

Note. Check for applicable Technical Service Bulletins (TSBs) before proceeding. DO NOT perform the following procedure if driveability conditions are not present. DO NOT turn ignition off during the following procedure or clear DTCs unless instructed to do so.

1. Verify customer complaint and conditions under which fault appears. Attempt to start engine. If engine starts, go to next step. If engine does not start, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
2. Check to see if MIL (CHECK ENGINE) light on instrument cluster illuminates, indicating a system fault. If MIL (CHECK ENGINE) light illuminates, go to next step. If MIL (CHECK ENGINE) light does not illuminate, go to MALFUNCTION INDICATOR LIGHT DIAGNOSIS in TROUBLE SHOOTING - NO CODES article.
3. Turn ignition off. Prepare Subaru Select Monitor (SSM) by inserting appropriate diagnostic cartridge and connecting diagnostic cable. Connect SSM or OBD-II generic scan tool to data link connector (DLC). Turn ignition and scan tool on. Retrieve diagnostic trouble codes (DTCs). If any DTCs are stored, save freeze frame data using scan tool MODE $02, then go to next step. If no DTCs are stored, although MIL (CHECK ENGINE) light is illuminated, go to MALFUNCTION INDICATOR LIGHT DIAGNOSIS in TROUBLE SHOOTING - NO CODES article.
4. Perform required repair by using procedure associated with DTC retrieved. See «SUBARU DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION CHART»(ref-11745-S06869871232001010800000) . If an automatic transaxle DTC is set with other codes, perform basic A/T checks and repair other DTCs first. Basic A/T checks consist of transaxle fluid level, differential fluid level, transaxle fluid leak, differential fluid leak, stall test, line pressure test, transfer clutch pressure test, time lag test, road test and shift characteristics only. See appropriate AUTOMATIC TRANSAXLE OVERHAUL article in AUTOMATIC TRANSMISSIONS.
5. After repair, perform clear memory function. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-11745-S21987207372000112700000) . After clearing DTCs, verify effectiveness of repair. See «VERIFICATION PROCEDURE»(ref-11745-S19795024722001010900000) . If repair addresses all issues and no DTCs exist, turn ignition off. Turn scan tool off. Disconnect test mode connector under driver's side of instrument panel. Disconnect scan tool from DLC.

CLEARING DIAGNOSTIC TROUBLE CODES

Clear DTC(s) using scan tool (MODE $04). Refer to scan tool manufacturer's instruction. After clearing memory, initialize idle speed control (ISC) motor. See ISC INITIALIZATION under PROGRAMMING.

OBD-II Generic Scan Tool Procedure

1. Turn ignition off. Connect test mode connector leads together under left side of instrument panel. see scheme 3and see scheme 4. Connect scan tool to DLC. On A/T vehicles, ensure selector lever is in "P" position. On M/T vehicles, depress clutch pedal. On all vehicles, start engine.
2. Using selector (A/T) or shift (M/T) lever, turn "P" and "N" position switches on. Depress brake pedal on A/T vehicles to turn brake switch on. On all vehicles, maintain engine speed at 2500-3000 RPM for 40 seconds. On vehicles not equipped with a tachometer, use a secondary pick-up type tachometer to monitor engine speed.
3. Place transaxle in "D" position (A/T) or first gear (M/T) and drive vehicle at 3-6 MPH. On all-wheel drive vehicles, release parking brake. On all vehicles, DTCs will be displayed if problems are still present. Record codes as required. This verification procedure may cause ABS warning light to illuminate due to speed variations between front and rear wheels. Clear ABS memory. See appropriate ANTI-LOCK article in BRAKES.

DIAGNOSTIC TROUBLE CODE DEFINITIONS

SUBARU DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION CHART

DIAGNOSTIC TESTS

Note. Subaru Select Monitor (SSM) or OBD-II generic scan tool must be used to perform diagnostic tests. Values and procedures given in tests are based on the use of SSM scan tool. Follow scan tool manufacturer's instructions. After repair or replacement of faulty parts, clear memory and perform verification of repair. For ECM terminal identification, see PIN VOLTAGE CHARTS article. If backprobing ECM connector is required, use ECM terminal identification illustration or reverse image of (Scheme 11). For circuit identification and wire colors, see WIRING DIAGRAMS article.

Scheme 11

Scheme 12

1. Perform basic diagnostic procedure. See «BASIC DIAGNOSTIC PROCEDURE»(ref-11745-S33755862182000112700000). If DTC P0141 and P1132 exist at the same time, go to next step. If only DTC P1132 exists, go to step 5.
2. Turn ignition off. Disconnect front HO2S connector. Turn ignition on. Using DVOM connected to ground, measure voltage at front HO2S connector terminal No. 2. (Scheme 12) If voltage is more than 10 volts, go to next step. If voltage is not more than 10 volts, locate and repair open circuit in wiring and check for proper terminal contact in connectors between front HO2S and main relay. See WIRING DIAGRAMS article.
3. Turn ignition off. Using an ohmmeter connected to ground, backprobe ECM connector B134 (35-pin connector) terminal No. 35. (Scheme 11) If resistance is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, locate and repair open circuit in wiring and check for proper terminal contact in connectors between ECM and chassis ground point.
4. Turn ignition off. Using an ohmmeter connected to ground, backprobe ECM connector B134 (35-pin connector) terminal No. 34. If resistance is less than 5 ohms, go to next step. If resistance is not less than 5 ohms, locate and repair open circuit in wiring and check for proper terminal contact in connectors between ECM and chassis ground point.
5. Start engine. Using scan tool, observe front HO2S heater current value. If current draw is more than 0.2 amp, check for poor contact at ECM and HO2S connectors. If current draw is not more than 0.2 amp, go to next step.
6. With engine idling, measure voltage between ground and ECM connector B134 (35-pin connector) terminal No. 22. If voltage is less than one volt, go to step 8. If voltage is not less than one volt, go to next step.
7. With engine idling, measure voltage between ground and ECM connector B134 (35-pin connector) terminal No. 22 while wiggling harness and ECM connector. If voltage changes less than one volt while wiggling harness and connector, check for poor terminal contact at ECM connector. If voltage does not change less than one volt while wiggling harness and connector, go to next step.
8. Measure voltage between ground and ECM connector B134 (35-pin connector) terminal No. 23. If voltage is less than one volt, go to step 10. If voltage is not less than one volt, go to next step.
9. Measure voltage between ground and ECM connector B134 (35-pin connector) terminal No. 23 while wiggling harness and ECM connector. If voltage changes less than one volt while wiggling harness and connector, check for poor terminal contact at ECM connector. If voltage does not change less than one volt while wiggling harness and connector, go to next step.
10. Turn ignition off. Measure resistance between front HO2S connector terminals No. 2 and No. 5. (Scheme 12) If resistance is less than 10 ohms, locate and repair open or short to ground in wiring and check for proper terminal contact in connectors between ECM and front HO2S. If resistance is not less than 10 ohms, replace front HO2S. Clear memory and perform verification procedure. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-11745-S21987207372000112700000) and «VERIFICATION PROCEDURE»(ref-11745-S19795024722001010900000).