INTRODUCTION
If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES proceed with self-diagnostics. If no fault codes or only pass codes are present, proceed to TESTS W/O CODES article in the ENGINE PERFORMANCE Section 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, Electronic Control Module (ECM) 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 intermittent fault goes away. However, the corresponding trouble code will be retained in Electronic Control Module (ECM) memory. If related fault does not reoccur within a certain time frame, related trouble code will be erased from ECM memory. Intermittent failures may be caused by a sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES article in the ENGINE PERFORMANCE Section.
Scheme 41
- The CHECK ENGINE light will come on when ignition is on and engine is not running. When engine is started, CHECK ENGINE light should go off. If light remains on while engine is running, a trouble code is present.
- If light did not come on with key on and engine off, the CHECK ENGINE light circuit must be checked before continuing. See appropriate INITIAL DIAGNOSTIC PROCEDURE in this article if CHECK ENGINE light failed to operate. The initial diagnostic procedure is located with code charts.
- To retrieve codes, turn ignition off. Install fuse in diagnosis terminal at the fuse block, located behind left side of instrument panel. (Scheme 41) Turn ignition on and count number of flashes from CHECK ENGINE light.
- As an example, a Code 21 will be identified by a flash, flash, pause and flash. A long pause will exist and Code 21 will be repeated 3 times. (Scheme 42) Each additional code will flash 3 times.
- If system is operating properly (with no codes), a Code 12 should exist with ignition on and engine off. This indicates the diagnostic system is capable of storing codes.
- Once all codes are displayed, codes will be repeated. Remove fuse from diagnostic terminal in fuse block after codes are recorded.
Scheme 42
CLEARING TROUBLE CODES
| CAUTION | Ensure ignition is off when disconnecting or reconnecting power supply for ECM. |
After repairs are performed, clear ECM memory of all stored trouble codes. To clear memory, turn ignition off. Disconnect negative battery cable for at least 30 seconds (Swift DOHC) or 60 seconds (Swift SOHC).
ECM LOCATION
ECM is located in upper left corner of instrument panel.
SUMMARY
If no hard fault codes (or only pass codes) are present, driveability symptoms exist or intermittent codes exist, proceed to TESTS W/O CODES article in this section for diagnosis by symptom (i.e. ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.
DIAGNOSTIC TROUBLE CODE DEFINITIONS
| Code | Description |
|---|---|
| 12 | System Normal |
| 13 | Oxygen Sensor Circuit |
| 14 | Coolant (Water) Temp Sensor (WTS) Indication Low |
| 15 | Coolant (Water) Temp Sensor (WTS) Indication High |
| 21 | Throttle Position Sensor Voltage High - A/T |
| 22 | Throttle Position Sensor Voltage Low - A/T |
| 23 | Air Temp Sensor (ATS) Circuit Indication Low |
| 24 | Speed Sensor Circuit Check |
| 25 | Air Temp Sensor (ATS) Circuit Indication High |
| 31 | Pressure Sensor (PS) Signal Voltage Low |
| 32 | Pressure Sensor (PS) Signal Voltage High |
| 41 | No Ignition Signal |
| 42 | Crank Angle Sensor |
| 51 (1) | EGR System Circuit Check |
| (1) Applicable to California models only. | |
| (1) | Applicable to California models only. |
DIAGNOSTIC TROUBLE CODE DEFINITIONS
Scheme 43
Scheme 44
Scheme 45
Scheme 46
Scheme 47
Scheme 48
Scheme 49
CODE 13 - OXYGEN SENSOR CIRCUIT
Before diagnosing trouble according to flow chart, check to make sure that the following system and parts other than EFI system are in good condition
- Air cleaner (clogged)
- Vacuum leaks (air inhaling)
- Spark plugs (contamination, gap)
- High-tension wires (cracks, deterioration)
- Distributor rotor or cap (wear, cracks)
- Ignition timing
- Engine compression
- Any other system and parts which might affect A/F mixture or combustion
If code No. 13 and another code are indicated together, the latter code has priority. Therefore, check and correct what is represented by that code first and then proceed to with code 13 check.
Be sure to use a voltmeter with high impedance (10,000 ohm/volt minimum) or digital volt ohmmeter for accurate measurement.
Scheme 50
Scheme 51
CODE 14 - COOLANT (WATER) TEMP SENSOR (WTS) INDICATION LOW
Note. When code 14, 23 and 32 are indicated together, it is possible that Light Green/Black wire is open or terminal A16 connection is poor.