Circuit/System Testing

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. 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 overdue for changing, can greatly affect the performance of the camshaft actuator.

Ignition OFF, disconnect C112.
Test for less than 1 ohm between the low reference circuit ECM side, terminal E and ground.
- If greater than 1 ohm, 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 (RPO LY2/LC9/LY5/LMG) or Water Pump Removal (RPO LY6/L76/L92) .
Inspect and test the remaining wire harness from C112 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, then refer to Camshaft Position Actuator Magnet Cleaning and Inspection and Camshaft Position Actuator Solenoid Valve Inspection (On-Vehicle) or Camshaft Position Actuator Solenoid Valve Inspection (Off-Vehicle) .