Harness Check
- If during SELF-DIAGNOSTICS testing, Electronic Control Unit (ECU) 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 ECU, check all components in suspected circuit. If components are okay, carefully disconnect ECU from vehicle harness.
- Inspect ECU harness connector and ECU contact pins for corrosion. Clean harness connector and ECU contact pins with contact cleaner.
- Inspect ECU harness connector for bent pins, missing pins and broken wires. Repair or replace as necessary.
- Connect ECU harness connector to ECU 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 ECU.