1. Check for continuity between the No. 22 terminal of the audio-HVAC module 22P connector and body ground.

Is there continuity?

YES | - | Check for loose wires or poor connections at the audio-HVAC module 22P connector. If the connections are good, substitute a known-good audio-HVAC module, and recheck. If the symptom/indication goes away, replace the original printed circuit board.■
NO | - | Check for an open in the wire between the audio-HVAC module and body ground. If the wire is OK, check for poor ground at G503.■