Entering Diagnostic Mode
- Turn ignition "ON". "CHECK ENGINE" lamp should glow. Locate diagnostic terminal taped on wire harness near ECM. Start engine. Connect terminals together and note "CHECK ENGINE" lamp.
- If any trouble codes are stored in ECM memory, the "CHECK ENGINE" lamp will flash 2-digit codes. Trouble codes will be displayed from lowest to highest numbered code (3 times each) and be repeated as long as the diagnostic terminals are connected.
ECM TROUBLE CODE IDENTIFICATION
| Code | Circuit Affected |
|---|---|
| 12 | Idle Position Switch - High Output |
| 13 | Idle Position Switch - Low Output |
| 14 | Wide Open Throttle Switch - High Output |
| 15 | Wide Open Throttle Switch - Low Output |
| 21 | Vacuum Control Solenoid - High Output |
| 22 | Vacuum Control Solenoid - Low Output |
| 23 | Incorrect Oxygen Sensor Reading |
| 24 | Incorrect Coolant Temperature Switch Reading |
| 25 | RAM Error |