Circuit/System Testing
WARNING: This page is about a different car, the 2009 GMC Sierra and 2009 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect the ECM connector (X3).
- Ignition ON, measure the voltage on the harness of the ECM connector (X3-66) for 5 V.
- If you have 5 V, test or replace the ECM.
- If the value is other than 5 V, test harness for:
- Short to Voltage
- Short to Ground
- Open
- If no trouble found, replace the TCM.