Circuit/System Verification

WARNING: This page is about a different car, the 2008 Cadillac XLR. However, it is still accessible from the selected car via links, so may be relevant.

Attempt to communicate with all modules on the high speed GMLAN bus.

If any high speed module communicates and any DTC beginning with a U exists, refer to Diagnostic Trouble Code (DTC) List - Vehicle for diagnostics.
If any high speed module communicates and no DTC beginning with a U exists, refer to DTC U0100-U0299 for diagnostics.