| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connector 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 COMPUTER RELEARN PROCEDURES - IMPORT article in GENERAL INFORMATION. |
Circuit Description
The ECM uses pick-up coil input signals to switch primary ignition circuit on and off. Primary circuit is turned off when ECM delivers a signal to ignitor on IGT wire, causing ignition coil to fire spark plug. After delivering a command to turn off primary circuit on IGT wire, ECM monitors Ignition Confirmation Signal (IGF) circuit to ensure primary switching occurred. If IGF signal is not input to ECM, ECM will stop fuel injection as a fail safe function. DTC is set if there is no IGF signal to ECM for 2 or more ignition cycles and this is repeated 3 times during 6 consecutive IGT signals with engine running. Possible causes are
- Faulty ignition system.
- Open or short in IGF or IGT circuit.
- Faulty ignitor.
- Faulty ignition coil.
- Faulty ECM.
Diagnostic Aids
Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.