Circuit/System Testing

WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.

IMPORTANT: You must perform the Circuit/System Verification first.

IMPORTANT: Incorrect engine oil viscosity, aftermarket engine oil additives, or engine oil that is overdue for changing, can greatly affect the performance of the camshaft actuator.

Ignition OFF, open the hood to disable the Auto-Stop function. Refer to Hybrid Modes of Operation Description .
Ignition ON, verify the scan tool hood position parameter displays Open.
- If the hood position does not display Open, refer to Diagnostic Trouble Code (DTC) List - Vehicle for DTC P254F.
Ignition OFF, disconnect X112.
Test for less than 3 ohms between the low reference circuit ECM side, terminal 1 and ground.
- If greater than 3 ohms, test the low reference 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 .
Inspect and test the remaining wire harness from X112 to the CMP solenoid for an open/high resistance or a short to ground.
- If the circuit tests normal, perform the Component Testing for the CMP actuator solenoid.
- If the CMP solenoid and the circuit test normal, refer to Camshaft Position Actuator Magnet Cleaning and Inspection and Camshaft Position Actuator Solenoid Valve Inspection (Off-Vehicle) .