Diagnostic Aids

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.

When testing circuits to the SDGM access can be accomplished by removing the instrument panel center trim panel. Note that this procedure does not allow removal of the SDGM, only access to the connector. Refer to Instrument Panel Center Trim Panel Replacement (with RPO SLT) .
DTC U1816 can set current in the HPCM, ECM, and the SDGM.
If DTC U1816 is only set in the HPCM, the PIM must be replaced due to all circuits between the HPCM and MCM being internal to the PIM.