INTRODUCTION
If no faults were found while performing BASIC DIAGNOSTICS , proceed with self-diagnostics. If no fault codes or only pass codes are present after entering self-diagnostics, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.).
HARD FAILURES
Hard failures cause CHECK ENGINE light to illuminate and remain on until problem is repaired. If light comes on and remains on (light may flash) during vehicle operation, cause of malfunction must be determined using diagnostic (code) charts. If a sensor fails, control unit will use a substitute value in its calculations to continue engine operation. In this condition, commonly known as limp-in mode, the vehicle runs but driveability will not be optimum.
INTERMITTENT FAILURES
Intermittent failures may cause CHECK ENGINE light to flicker or illuminate and go out after the intermittent fault goes away. However, the corresponding trouble code will be retained in ECU memory. If related fault does not reoccur within a certain time frame, related trouble code will be erased from ECU memory. Intermittent failures may be caused by a sensor, connector or wiring related problems. See INTERMITTENTS in the SYSTEM/COMPONENT TESTS article in the ENGINE PERFORMANCE section.
RETRIEVING CODES
- Enter specific test mode by connecting or disconnecting read memory and/or test mode connectors as shown in «RELATIONSHIP BETWEEN MODES & CONNECTORS»(/subaru/legacy/bcbjbf-1989-1994/remont/testing-diagnostics/#engine-controls-tests-wcodes) table. Connectors are located behind left side of dash. (Scheme 48)
- Observe either CHECK ENGINE or O2 sensor monitor light. Note trouble codes, if any. Long illumination periods of 1.2 seconds designate the tens digit in the numbered codes. Short illumination periods of.2 second designate the ones digit in the numbered codes.
- Tens and one digits are separated by a.03-second interval of non illumination. Example: 3 long flashes (1.2 seconds each), followed by 5 short flashes (.02 second each) designate code 35.
- Code is repeated after a break of 2 seconds, unless another code is present which will be displayed after the 2-second break. Once all codes have been displayed, sequence will repeat.
Scheme 48
| Mode | Read Memory Connector | Test Mode Connector |
|---|---|---|
| U-CHECK (1) | Disconnected | Disconnected |
| READ MEMORY (1) | Connected | Disconnected |
| D-CHECK (1) | Disconnected | Connected |
| CLEAR MEMORY (2) | Connected | Connected |
| (1) Key on, engine off. (2) Key on, engine running. | ||
| (1) | Key on, engine off. |
| (2) | Key on, engine running. |
RELATIONSHIP BETWEEN MODES & CONNECTORS
TROUBLE CODE IDENTIFICATION
| Code | Circuit Affected | Probable Cause |
|---|---|---|
| 11 | Crank Angle Sensor | No Reference Signal |
| 12 | Starter Switch | Open/Short Circuit |
| 13 | Cam Angle Sensor | No Position Pulse |
| 14 | Fuel Injector No. 1 | Inoperative Fuel Injector |
| 15 | Fuel Injector No. 2 | Inoperative Fuel Injector |
| 16 | Fuel Injector No. 3 | Inoperative Fuel Injector |
| 17 | Fuel Injector No. 4 | Inoperative Fuel Injector |
| 21 | Coolant Temperature Sensor | Open/Short Circuit |
| 22 | Knock Sensor | Open/Short Circuit |
| 23 | Airflow Meter Circuit | Open/Short Circuit |
| 24 | Air Control Valve | Inoperative Air Control Valve |
| 31 | Throttle Position Sensor | Open/Short Circuit |
| 32 | Oxygen (O2) Sensor | Abnormal Sensor Signal |
| 33 | Vehicle Speed Sensor | No Reference Signal |
| 35 | Purge Control Solenoid Valve | Open/Short Circuit |
| 41 | Air/Fuel Ratio Control System | Faulty Learning Control Function |
| 42 | Idle Switch | Abnormal Reference Signal |
| 44 | Wastegate Duty Solenoid (Turbo) | Open/Short Circuit |
| 45 | Atmospheric Pressure Sensor (1) | Faulty Sensor |
| 45 | Pressure Sensor Duty Solenoid | Valve Inoperative |
| 49 | Airflow Sensor | Use of Improper Airflow Sensor |
| 51 | Neutral Safety Switch (M/T) | Open/Short Circuit |
| 51 | Inhibitor Switch (A/T) | Open/Short Circuit |
| 52 | Parking Brake Switch (A/T) | Open/Short Circuit |
| (1) Non-turbo models. | ||
| (1) | Non-turbo models. |
TROUBLE CODE IDENTIFICATION
SPECIFICATION CODES IDENTIFICATION
Specification codes are codes accessed with trouble code(s) from ECU. These codes determine transmission and vehicle emissions application. Specification code is not available on carbureted models.
| Code | Application |
|---|---|
| 01 | M/T (Non-Turbo), Canada & Fed. |
| 02 | M/T (Non-Turbo), Calif. |
| 03 | A/T (Non-Turbo), Canada & Fed. |
| 04 | A/T (Non-Turbo), Calif. |
| 05 | M/T (Turbo), Canada & Fed. |
| 06 | M/T (Turbo), Calif. |
| 07 | A/T (Turbo), Canada & Fed. |
| 08 | A/T (Turbo), Calif. |
| (1) Specification codes are accessed with trouble codes through CHECK ENGINE or O2 monitor light. | |
| (1) | Specification codes are accessed with trouble codes through CHECK ENGINE or O2 monitor light. |
SPECIFICATION CODES (1)
CLEARING CODES
After malfunction has been corrected, trouble code will clear from memory when CLEAR MEMORY mode is accessed. Unless all items check okay in D-CHECK mode, memory will not be cleared. Refer to the RELATIONSHIP BETWEEN MODES & CONNECTORS table.
ECM LOCATION
Legacy ECM is located behind the left dash panel.
SUMMARY
If no hard fault codes (or only pass codes) are present, driveability symptoms exist or intermittent codes exist, proceed to the TESTS W/O CODES article in the ENGINE PERFORMANCE Section for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.
| Abbreviation | Color |
|---|---|
| BR | Black/Red |
| BW | Black/White |
| BY | Black/Yellow |
| G | Green |
| GB | Green/Black |
| GL | Green/Blue |
| GR | Green/Red |
| GW | Green/White |
| GY | Green/Yellow |
| Lg | Light Green |
| LgB | Light Green/Black |
| LR | Blue/Red |
| LW | Blue/White |
| LY | Blue/Yellow |
| RY | Red/Yellow |
| W | White |
| WB | White/Black |
| WR | White/Red |
| WY | White/Yellow |
| Y | Yellow |
| YL | Yellow/Blue |
| YR | Yellow/Red |
| YW | Yellow/White |
WIRE COLOR ABBREVIATIONS
DIAGNOSTIC CODE CHARTS
Note. Refer to appropriate SYSTEM/COMPONENT TESTS and PIN VOLTAGE CHART S articles for test values when requested by following diagnostic flow charts.
- For 1990 models, see: «PIN VOLTAGE CHARTS»(ref-25949) and «SYSTEM/COMPONENT TESTS»(/subaru/legacy/bcbjbf-1989-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) .
- For 1991 models, see: «PIN VOLTAGE CHARTS»(/subaru/legacy/bcbjbf-1989-1994/remont/pin-voltage-charts/#engine-controls-pin-voltage-charts) and «SYSTEM/COMPONENT TESTS»(/subaru/legacy/bcbjbf-1989-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) .
Note. The following diagnostic flow charts and mini-schematics are courtesy of Subaru of America, Inc.
With A "NO TROUBLE" Condition
| Engine & Connector Conditions | CHECK ENGINE Light should Be | O2 Monitor Light Should Read |
|---|---|---|
| U-Check Mode, Engine Off, Ignition Switch On, Read Memory Connector Disconnected, Test Mode Connector Disconnected | On | Vehicle Specification Code Displayed |
| U-Check Mode, Engine On, Read Memory Connector Connected, Test Mode Connector Disconnected | Off | O2 Monitor |
| Read Memory, Engine Off, Ignition Switch On, Read Memory Connector Connected, Test Mode Connector Disconnected | Blinking | Vehicle Specification Code Displayed |
| Read Memory, Engine On, Read Memory Connector Connected, Test Mode Connector Disconnected | Blinking | O2 Monitor |
| D-Check, Engine Off, Ignition Switch On, Read Memory Connector Disconnected, Test Mode Connector Connected | On | Vehicle Specifications Code Displayed |
| D-Check, Engine On, Read Memory Connector Disconnected, Test Mode Connector Connected | (1) Vehicle Specs Code Displayed | Vehicle Specs Code Displayed |
| Clear Memory, Engine Off, Ignition Switch On, Read Memory Connector Connected, Test Mode Connector Connected | On | Vehicle Specifications Code Displayed |
| Clear Memory, Engine On, Read Memory Connector Connected, Test Mode Connector Connected | (1) Vehicle Specs Code Displayed | Vehicle Specs Code Displayed |
| (1) When the engine operates at a speed greater than 2000 RPM for more than 40 seconds, the check engine light blinks. However, when all check items check out "OK", even before the 40 seconds is reached, the check engine light blinks. | ||
| (1) | When the engine operates at a speed greater than 2000 RPM for more than 40 seconds, the check engine light blinks. However, when all check items check out "OK", even before the 40 seconds is reached, the check engine light blinks. |
BASIC OPERATION OF SELF-DIAGNOSTIC SYSTEM - NO TROUBLE MENU
During "TROUBLE" Condition
| Engine & Connector Conditions | CHECK ENGINE Light should Be | (O2 Monitor) Should Read |
|---|---|---|
| U-Check, Engine Off, Ignition Switch On, Read Memory Connector Disconnected, Test Mode Connector Disconnected | On | Vehicle Specifications Code Displayed |
| Read Memory, Ignition Switch On, Read Memory Connector Connected, Test Mode Connector Disconnected | Trouble Code (Memory) | Trouble Code (Memory) |
| D-Check, Engine On, Read Memory Connector Disconnected, Test Mode Connector Connected | (1) Trouble Code | (1) Trouble Code |
| Clear Memory, Engine On, Read Memory Connector Connected, Test Mode Connector Connected | (1) Trouble Code | (1) Trouble Code |
| (1) When the engine operates at a speed greater than 2000 RPM for more than 40 seconds, a trouble code is displayed. | ||
| (1) | When the engine operates at a speed greater than 2000 RPM for more than 40 seconds, a trouble code is displayed. |
BASIC OPERATION OF SELF-DIAGNOSTIC SYSTEM - TROUBLE MENU
U-MODE CHECK
The U-check is a user-oriented mode in which only the MPFI componants necessary for start-up and drive are diagnosed.
READ MEMORY MODE
The mode is used to read past problems (even when the vehicles monitor lamps are off). It is most effective in detecting poor contact or loose connections of connectors, harnesses etc.
Flow Chart - Read Memory Mode. Scheme 49
D-CHECK MODE
Note. When the engine operates at a speed greater than 2000 RPM for more than 40 seconds, a trouble code is displaued, or the check engine light blinks. However, when all check items check out "OK", even before the 40 seconds is reached, the check engine light blinks.
Flow Chart - D-Check Mode. Scheme 50
CLEAR MEMORY MODE
Note. When the engine operates at a speed greater than 2000 RPM for more than 40 seconds, a trouble code is displaued, or the check engine light blinks. However, when all check items check out "OK", even before the 40 seconds is reached, the check engine light blinks.
Flow Chart - Clear Memory Mode. Scheme 51
Schematic - Code 11, Crank Angle Sensor (Non-Turbo). Scheme 52
Schematic - Code 11, Crank Angle Sensor (Turbo). Scheme 53
Flow Chart - Code 11, Crank Angle Sensor. Scheme 54
Scheme 55
Schematic - Code 12, Starter Switch. Scheme 56
Flow Chart - Code 12, Starter Switch. Scheme 57
Scheme 58
Schematic - Code 13, CAM Angle Sensor (Non-Turbo). Scheme 59
Schematic - Code 13, CAM Angle Sensor (Turbo). Scheme 60
Flow Chart - Code 13, CAM Angle Sensor. Scheme 61
Scheme 62
Schematic - Codes 14, 15, 16 & 17, Fuel Injectors. Scheme 63
Flow Chart - Codes 14, 15, 16 & 17, Fuel Injectors. Scheme 64
Scheme 65
Schematic - Code 21, Coolant (Water) Temperature Sensor. Scheme 66
Flow Chart - Code 21, Coolant (Water) Temperature Sensor. Scheme 67
Scheme 68
Schematic - Code 22, Knock Sensor. Scheme 69
Flow Chart - Code 22, Knock Sensor. Scheme 70
Scheme 71
Schematic - Code 23, Airflow Meter Circuit. Scheme 72
Flow Chart - Code 23, Airflow Meter Circuit. Scheme 73
Scheme 74
Schematic - Code 24, Air Control Valve (Non-Turbo M/T). Scheme 75
Schematic - Code 24, Air Control Valve (Non-Turbo A/T). Scheme 76
Flow Chart - Code 24, Air Control Valve. Scheme 77
Scheme 78
Schematic - Code 31, Throttle Position Sensor. Scheme 79
Flow Chart - Code 31, Throttle Position Sensor. Scheme 80
Scheme 81
Schematic - Code 32, Oxygen (O2) Sensor. Scheme 82
Flow Chart - Code 32, Oxygen (O2) Sensor. Scheme 83
Scheme 84
Schematic - Code 33, Vehicle Speed Sensor. Scheme 85
Flow Chart - Code 33, Vehicle Speed Sensor. Scheme 86
Scheme 87
Schematic - Code 35, Canister Purge Control (CPC) Solenoid. Scheme 88
Flow Chart - Code 35, Canister Purge Control (CPC) Solenoid. Scheme 89
Scheme 90
Flow Chart - Code 41, Air/Fuel Ratio Control System. Scheme 91
Schematic - Code 42, Idle Switch. Scheme 92
Flow Chart - Code 42, Idle Switch. Scheme 93
Scheme 94
Schematic - Code 44, Wastegate Control Duty Sol. Valve. Scheme 95
Flow Chart - Code 44, Wastegate Control Duty Sol. Valve. Scheme 96
Schematic - Code 45, Pressure Sensor Duty Solenoid. Scheme 97
Scheme 98
CODE 45: ATMOSPHERIC PRESSURE SENSOR (NON-TURBO)
Code 45 indicates a faulty atmospheric pressure sensor inside the ECU. Symptoms include the following
- Rough or erratic idle.
- Failure of engine to start.
If a code 45 is displayed, replace the ECU.
CODE 49: AIRFLOW SENSOR
Code 49 indicates use of an improper airflow sensor. Symptoms include the following
- Rough or erratic idle.
- Failure of engine to start.
If a code 49 is displayed, check specifications of airflow sensor and ECU. Replace the airflow sensor or ECU with the correct type as follows
- Automatic Transmission - Hot film type airflow sensor (JECS).
- Manual Transmission - Hot wire type airflow sensor (Hitachi).
