Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Ignition OFF, disconnect C112.
- Test for less than 1 ohm between the low reference circuit terminal E and ground on the ECM side of harness.
- If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
- Verify the test lamp does not illuminate between the ground circuit terminal E and the control circuit D on the ECM side of harness.
- If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
- Remove the test lamp.
- Command the CMP actuator from zero to 25 degrees. Verify the scan tool CMP actuator ckt short to volts test status parameter is OK.
- If not the specified value, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.
- Install a 3A fused jumper wire between the control circuit terminal D and the low reference circuit terminal E on the ECM side of harness. Command the CMP actuator to 25 degrees with a scan tool. Verify the scan tool CMP actuator ckt short to volts test status parameter is displaying Fault.
- If not the specified value, test the control circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
- Remove the water pump from the engine. Refer to Water Pump Removal (RPO LY2/LH6/LMG/LY5/LC9) or Water Pump Removal (RPO LY6/L76/L92) .
- Inspect and test the remaining CMP solenoid wire harness from C112 to the CMP solenoid for a short to ground or an open/high resistance.
- If all circuits test normal, replace the CMP actuator solenoid.
IMPORTANT:
You must perform the Circuit/System Verification first.