TEST 6 (Will Not Flash Code 12)
- Check ECM fuse. With ignition on and engine stopped, ground ALDL terminal No. 1. Ground ECM connector terminal C45-1 and note "Check Engine" light. If "Check Engine" light does not flash code 12, go to step 2). If code 12 flashes, repair open in ALDL terminal No. 1 wire.
- Disconnect ECM connector C46. If light is off, replace ECM and repeat DIAGNOSTIC CIRCUIT CHECK. If light is on, repair grounded lead from "Check Engine" light and ECM connector terminal C46-4. Repeat DIAGNOSTIC CIRCUIT CHECK.
ECM TROUBLE CODE IDENTIFICATION
| Code | Problem |
|---|---|
| 12 | No Ignition Reference Pulse to ECM |
| 13 | Oxygen (O2) Sensor Circuit |
| 14 | Shorted Coolant Sensor Circuit |
| 15 | Open Coolant Sensor Circuit |
| 21 | Idle Switch Circuit Open or WOT Switch Circuit Shorted |
| 22 | Fuel Cut Solenoid Circuit Open or Grounded |
| 23 | Duty Solenoid Circuit Open or Grounded |
| 25 | Air Switching Solenoid Circuit Open or Grounded |
| 26 | Canister Purge Vacuum Switching Valve Circuit Open or Grounded |
| 27 | Constant High Voltage from VSV to ECM |
| 31 | No Ignition Reference Pulse to ECM at Part Throttle, Under Road Load |
| 32 | EGR or Sensor Circuit Failure |
| 34 | EGR Sensor Circuit Failure |
| 44 | Oxygen (O2) Sensor Lean Indication |
| 45 | Oxygen (O2) Sensor Rich Indication |
| 51 | Shorted Fuel-Cut Solenoid Circuit &/or Faulty ECM |
| 52 | Faulty ECM (RAM Problem in ECM) |
| 53 | Shorted Air Switching Solenoid &/or Faulty ECM |
| 54 | Shorted Duty Solenoid &/or Faulty ECM |
| 55 | Faulty ECM (A/D Converter in ECM) |