Diagnostic Aids
WARNING: This page is about a different car, the 2008 GMC Yukon and 2008 Chevrolet Tahoe. However, it is still accessible from the selected car via links, so may be relevant.
A poor connection at the B+ terminal of the APM or blown 200 Amp Mega-Fuse in the hybrid BEC will prevent the APM from powering up and all values in the APM data list will read zero on the scan tool.
A poor connection on the APM wake-up signal X1 Terminal 3 from the SDGM will also prevent the APM from powering up and all data values in the APM data list will read zero on the scan tool.