Electrical System Testing

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

If DTCs P3401, P3425, P3441, or P3449 are set, refer to DTC P3401, P3425, P3441, or P3449 .
Ignition ON, the engine OFF, command each VLOM solenoid ON and OFF using the scan tool output control function. While standing next to the engine compartment, you should be able to hear the solenoid energize and de-energize with each scan tool output control command.

If you cannot hear each solenoids energize and de-energize, then refer to Cylinder Deactivation (Active Fuel Management) System Diagnosis .