| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT. |
Note. For component location, see appropriate illustration in THEORY & OPERATION article.
Circuit Description
ECM determines ignition timing and outputs ignition signals (IGT) for each cylinder. Based on IGT signals, ignitor controls primary ignition signals (IGC) for all ignition coils. Ignitor also sends an ignition confirmation signal (IGF) as a fail-safe measure to the ECM. DTC is set when there is no IGF signal to ECM for 6 consecutive IGT signals during engine operation. Possible causes are
- IGF or IGT circuit from ignitor to ECM is open or shorted.
- Defective ignitor.
- Defective ECM.
Diagnostic Aids
Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.