Instrument Panel Cluster (IPC) and Engine Control Module (ECM) Functionality

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 all circuits referenced above check good use the scan tool under engine data 2 to see if the scan tool still indicates the vehicle is still in 2WD.

If the scan tool indicates the vehicle is in 2WD then replace the engine control module, if not then replace the IPC.