Chart A-6, Won't Flash Code 12
NOTE:
There should be a steady "CHECK ENGINE" light when ignition is on and engine is not running.
NOTE:
Test numbers refer to test numbers on diagnostic chart.
- This step checks for short to battery voltage in wire to terminal "C" or faulty light driver. Normal voltage is 9-11 volts.
- This step checks if problem is in ECM or light driver. Grounding terminal "C" should turn light off. If it does, problem is related to ECM and/or ECM wiring.
- Grounding terminal No. 2 at ECM and finding light on indicates an open in wire to terminal "C" of light driver.
- This step checks for open in wire from ECM to test terminal in ALCL connector. Code 12 should flash when terminal No. 16 is grounded.
- This test checks for voltage supply to ECM. Voltage should read over 9 volts.
- This test checks for a bad ground to the ECM. Terminal No. 1 is the engine ground. A good ground to the ECM will read less than one volt at terminal No. 1.
- This step distinguishes between a faulty ECM and PROM. Normal response is for Code 51 to flash even though the PROM is not installed in the ECM. If it doesn't, ECM is faulty.