Harness Check
- If during SELF-DIAGNOSTICS testing, engine Electronic Control Module (ECM) is found to be faulty, perform the following steps to confirm diagnosis.
- Most components are incorrectly diagnosed due to faulty electrical connectors or poor connections between component and vehicle.
- Sometimes, simply disconnecting and connecting an electrical component will provide a good electrical connection. Before replacing ECM, check all components in suspected circuit. If components are okay, carefully disconnect ECM from vehicle harness.
- Inspect ECM harness connector and ECM contact pins for corrosion. Clean harness connector and ECM contact pins with contact cleaner.
- Inspect ECM harness connector for bent pins, missing pins and broken wires. Repair or replace as necessary.
- Connect ECM harness connector to ECM and retest system with Diagnostic Readout Box (DRB-II) or similar scan tester. See appropriate TESTS W/CODES article in the ENGINE PERFORMANCE Section. If vehicle does not pass test and fails with the same message, replace ECM.