Self-Diagnostics - 2.0L: Diagnosis Subaru Impreza GD/GC/GG 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.

BASIC DIAGNOSTIC PROCEDURE

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.

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 57) For scan tool functions see SCAN TOOL USAGE.

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, see «NO-START DIAGNOSIS»(ref-157416-S17647741032003081200000) in BASIC DIAGNOSTIC PROCEDURES article.
2. Does the (CHECK ENGINE) Malfunction Indicator Light (MIL) illuminate, indicating a system fault? If yes, go to next step. If no, see «SYMPTOMS»(ref-157458-S35398019642003081400000) in TROUBLE SHOOTING - NO CODES article.
3. Turn ignition OFF. Connect the Subaru Select Monitor (SSM) or OBD-II generic scan tool to data link connector (DLC). Turn ignition and scan tool ON. Retrieve Diagnostic Trouble Codes (DTCs). Record any DTCs indicated on the scan tool. Repair the trouble cause. See «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158189-S29104350202003091700000) . After repairs are complete, go to next step. If no DTCs are indicted on the scan tool and (CHECK ENGINE) MIL is illuminated, see «MALFUNCTION INDICATOR LIGHT (MIL) DOES NOT GO OFF»(ref-158189-S21822071542003120400000) under SYSTEM CHECKS.
4. Perform the CLEAR MEMORY MODE. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-158189-S11955140522003091700000) . Perform the Inspection Mode. See «INSPECTION MODE»(ref-158189-S36786598432003091700000) under DRIVE CYCLES. If the scan tool indicates any DTCs, see «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158189-S29104350202003091700000) . If no DTCs are indicated on the scan tool, system is okay.

Scheme 57

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-158189-S29471765792003091700000) .
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-158189-S23206226382003091700000) and «INTERMITTENT FAILURES»(ref-158189-S09683016332003091700000) . For diagnosing hard codes, see «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158189-S29104350202003091700000) . For diagnosing intermittent codes, see «INTERMITTENTS»(ref-157458-S19658488182003081400000) in TROUBLE SHOOTING - NO CODES article
3. If no DTCs are present and a driveability problem exists, refer to «SYMPTOMS»(ref-157458-S35398019642003081400000) 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.

OBD-II General Scan Tool

Note. For details concerning Diagnostic Trouble Codes (DTCs), see DIAGNOSTIC TROUBLE CODE DEFINITIONS .

1. Prepare OBD-II General Scan Tool required by SAE J-1978.
2. Connect the OBD-II General Scan Tool to the Data Link Connector (DLC) located in the lower portion of the instrument panel, on the drivers side. (Scheme 57)
3. Using the OBD-II General Scan Tool, call up Diagnostic Trouble Codes (DTCs) and freeze frame data. OBD-II General Scan Tool functions consist of: MODE $01 Current Powertrain Diagnostic Data. Refers to data denoting the current operating condition of analog input/output, digital input/output and/or the powertrain system. (Scheme 58) MODE $02 Powertrain Freeze Frame Data. Refers to data denoting the operating condition when the trouble is sensed by the on-board diagnostic system. (Scheme 59) MODE $03 Emission-Related Powertrain DTCs. Refers to Read Diagnostic Trouble Code for information about data denoting emission-related powertrain DTCs. MODE $04 Clear/Reset Emission-Related Diagnostic Information. Refers to the mode used to clear or reset emission-related diagnostic information. Read out data according to repair procedures. For detailed operation procedures, refer to the OBD-II General Scan Tool Operation Manual.

Scheme 58

Scheme 59

Clear DTC(s) using Genera 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.

INSPECTION MODE

Preparation For Inspection Mode

Ensure fuel level remains at approximately half and battery voltage is 12 volts or more. Raise vehicle using a garage jack and place on safety stands or drive vehicle onto free rollers.

OBD-II Generic Scan Tool Procedure

After performing diagnostics and clearing the memory, check for any remaining unresolved trouble data.

1. Raise and suitably support vehicle, or place all wheels on rollers. Warm up the engine. Turn ignition OFF. Connect Test Mode Connector leads together under left side of instrument panel. see scheme 5
2. Connect OBD-II Generic Scan Tool to data link connector (DLC) located under left side of dash. (Scheme 57)
3. Start the engine. Ensure selector lever is placed in "P" position before starting on Automatic Transmission (A/T) vehicles. Depress the clutch pedal when starting the engine on Manual Transmission (MT) vehicles.
4. Using the selector lever or shift lever, turn the "P" position switch and "N" position switch to on.
5. Depress brake pedal on A/T vehicles to turn brake switch on.
6. 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.
7. 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. This inspection 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.
8. Using the OBD-II General Scan Tool, check for DTCs and record results. If any DTCs are present, see «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-158189-S29104350202003091700000).

DIAGNOSTIC TROUBLE CODE DEFINITIONS

SUBARU DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION CHART

Scheme 60

Scheme 61

Scheme 62

Scheme 63

Scheme 64

Scheme 65

Scheme 66

Scheme 67

Scheme 68

Scheme 69

Scheme 70

Scheme 71

Diagnosis

The CHECK ENGINE MIL circuit is open or shorted.

Trouble Symptom

When the ignition switch is turned ON, with engine off, MIL does not illuminate.

1. Check output signal form Engine Control Module (ECM). Turn ignition ON and measure the voltage between ECM connector B137, terminal No. 15 and chassis ground. If the measured value is less than 1.0 volt, go to step 4. If the measured value is more than 1.0 volt, go to next step. (Scheme 72)
2. Check for poor contact at ECM. If the MIL illuminates when shaking or pulling on the ECM connector, repair poor connection as necessary. If the MIL does not illuminate while shaking or pulling on the ECM connector, go to next step.
3. Check the ECM connector to ensure connector is properly connected. If the ECM connector is properly connected, replace the ECM. See «ENGINE CONTROL MODULE»(ref-161281-S31192852882004033100000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION article. If the ECM connector is not properly connected, repair connector as necessary.
4. Check harness between combination meter and ECM connector. Turn ignition OFF. Remove the combination meter and disconnect the connector. Disconnect the ECM connector. Measure the resistance between ECM connector B137, terminal No. 15 and combination meter connector i12, terminal No. 6. If the measured value is less than 1.0 ohm, go to next step. If the measured value is greater than 1.0 ohm, repair open circuit in harness between ECM and combination meter connector or poor contact in coupling connector. (Scheme 72)
5. Check for poor contact in combination meter connector. If there is a poor contact in the combination meter connector, repair as necessary. If combination meter connector is okay, go to next step.
6. Check harness between combination meter and ignition switch connector. Turn ignition switch ON. Measure the voltage between combination meter connector i10, terminal No. 7 and chassis ground. If the measured valve is more than 10 volts, replace combination meter. If measured value is less than 10 volts, replace blown fuse No. 13, repair open or short in harness between fuse No. 13 and ignition switch battery terminal, or repair poor contact in ignition switch. (Scheme 72)

Scheme 72

The CHECK ENGINE MIL circuit is shorted.

Although MIL comes on when the engine is running, a DTC is not shown on the Subaru Select Monitor or OBD-II General Scan Tool display.

Check the harness between combination meter and ECM connector. Turn the ignition OFF. Disconnect the connector form the ECM. Turn the ignition ON. If the MIL illuminates, repair the short in the harness between the combination meter and the ECM connector. (Scheme 72) If the MIL does not illuminate, replace the ECM. See ENGINE CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION article.

The CHECK ENGINE MIL circuit is open or shorted. Test Mode Connector is open.

When in inspection mode, MIL does not blink at a cycle of 3 Hz.

1. Check status of CHECK ENGINE MIL. Turn ignition OFF. Disconnect the Test Mode Connector. Turn ignition ON, engine off. If MIL alienates, go to next step. If MIL does not illuminate, see «MALFUNCTION INDICATOR LIGHT (MIL) DOES NOT COME ON»(ref-158189-S11052637522003120400000).
2. Check harness between combination meter and ECM connector. (Scheme 73) Turn ignition OFF. Disconnect ECM connector. Turn ignition ON. If MIL illuminates, repair short to ground in harness between combination meter and ECM connector. If MIL does not illuminate, go to next step.
3. Check harness between Test Mode Connector and chassis ground. Turn ignition OFF. Disconnect ECM connector. Measure the resistance between test harness connector B76, terminal No. 1 and chassis ground. (Scheme 73) If the measured value is less than 1 ohm, go to next step. If measured resistance is more than 1 ohm, repair open in harness between Test Mode Connector and chassis ground.
4. Check for poor contact in the ECM connector. If there is a poor contact in the ECM connector, repair as necessary. If ECM connector is okay, go to next step.
5. Check harness between ECM and Test Mode Connector. Connect the Test Mode Connector. Measure the resistance between ECM connector B134, terminal No. 14 and chassis ground. (Scheme 73) If the measured value is less than 1 ohm, go to next step. If the measured value is more than 1 ohm, repair open between ECM and Test Mode Connector.
6. Check for poor contact in ECM connector. If there is a poor contact in the ECM connector, repair as necessary. If ECM connector is okay, replace ECM. See «ENGINE CONTROL MODULE»(ref-161281-S31192852882004033100000) under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION article.

Scheme 73

Test Mode Connector circuit is shorted.

MIL blinks at a cycle of 3 Hz when the ignition is on.

1. Check Test Mode Connector. Disconnect the Test Mode Connector, Turn ignition ON. If the MIL blinks ON and OFF, go to next step. If MIL does not blink ON and OFF, system is okay.
2. Check harness between ECM connector and engine ground terminal. Turn ignition OFF. Disconnect the ECM connector. Measure the resistance between ECM connector B134, terminal No. 14 and chassis ground. If the measured value is less than 5 ohms, repair short in harness between ECM and Test Mode Connector. If measured value is greater than 5 ohms, replace ECM. See «ENGINE CONTROL MODULE»(ref-161281-S31192852882004033100000) under COMPUTERIZED ENGINE CONTROLS article.

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 68). For circuit identification and wire colors, see ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. For component locations (Scheme 60)- (Scheme 67).

Note. For diagnosis, see DTC P0130 .

Note. For diagnosis of DTC P0171, see DTC P0172

Note. For DTC P0731 diagnosis, see DTC P0734 .

Note. For DTC P0732 diagnosis, see DTC P0734 .

Note. For DTC P0733 diagnosis, see DTC P0734 .

DTC 1301: MISFIRE DETECTED (HIGH TEMPERATURE EXHAUST GAS)

For diagnosis see scheme 144and (Scheme 74).

Scheme 74

DTC 1312: EXHAUST GAS TEMPERATURE SENSOR MALFUNCTION

For diagnosis see scheme 144and (Scheme 75).

Scheme 75

Note. On A/T vehicles, place transmission in "P" or "N". On M/T vehicles, depress clutch pedal.

Perform basic diagnostic procedure. See BASIC DIAGNOSTIC PROCEDURE . Attempt to start engine. If starter operates in START position, locate and repair short to ground or open in wiring between ECM and starter. If starter does not operate in START position, check starter circuit. Clear memory and perform verification procedure. See CLEARING DIAGNOSTIC TROUBLE CODES and INSPECTION MODE .