Conditions for Setting the DTC

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.

The HPCM does not receive voltage from the SDGM on the wake up signal circuit.
The wake up circuit between the SDGM and the APM is shorted to voltage.
Any of the 4 PTLAN circuits connected to the HPCM are open.