Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Sierra and 2008 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
IMPORTANT:
You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.
Testing the Ignition 1 Signal Circuit
- Ignition ON, verify that B+ is available to both test points of the fuse from the powertrain relay to the ECM.
- If B+ is only available on one test point of the fuse, test the ignition 1 voltage circuit from the fuse to the ECM for a short to ground. If the circuit tests normal, replace the ECM.
- If B+ is not available on either test point of the fuse, replace the underhood fuse block.
- Ignition OFF, disconnect the ECM C1 connector.
- Ignition ON, verify that B+ is available at C1-19.
- If B+ is not available, test the ignition 1 voltage circuit for an open/high resistance condition. If the circuit tests normal, replace the ECM.
- If all circuits test normal, replace the ECM.
IMPORTANT:
A resistance of 5 ohms or greater in the circuit will cause the DTC to set.
Testing the EC Ignition Relay Feedback Circuit
- Ignition OFF, remove the powertrain relay from the underhood fuse block.
- Ignition ON, connect a 3A fused jumper wire from B+ to the powertrain ignition 1 voltage circuit terminal. Verify that the EC Ignition Relay Feedback parameter displays B+ on the scan tool.
- If the scan tool parameter is less than the specified value, test the ignition 1 voltage circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the ECM.
IMPORTANT:
A resistance of 5 ohms or greater in the circuit will cause the DTC to set.