Circuit/System Testing
- With the engine running, observe the applicable Cylinder IC Circuit Status parameters with the scan tool.
- If a parameter displays short Gnd/Open, test for an open/high resistance or a short to ground in the affected IC circuit. All wire circuit resistance should measure less than 2 ohms.
- If a parameter displays short to B+, test for a short to voltage in the affected IC circuit.
- Connect jumper wires from the harness connector of the ICM to the corresponding terminals of the ICM.
- Using the jumper wires, exchange the affected IC control circuit with a known good IC control circuit. Also exchange the spark plug wires of the corresponding coils.
- Start the engine.
- Observe the Misfire Current counters with the scan tool.
- If the misfire transfers with the suspect IC control circuit, replace the ECM.
- If the misfire remains with the coil, replace the ICM.
IMPORTANT:
An open/high resistance on the low reference circuit to the ICM may cause a misfire.