Problem: The customer brought the vehicle in because the power window, sunroof and mirrors were not working. All three stopped working at the same time.
Details: The technician checked all of the modules but found no diagnostic trouble codes (DTCs). Next he used the scan tool to check for communication with the Body Control Module (BCM) and driver door module (DDM). The BCM communicated with the scan tool but the DDM would not. After looking at the wiring diagram, the technician decided to check the power and ground connections at the DDM.
Confirmed Repair: In this case, the technician found the ignition switch signal wire (yellow wire on pin A25) to the DDM was broken at the driver door connector (see image). After repairing the wire, all of the components began working normally.
Diagnostic Insight: You may wonder how this ignition signal wire failure could have caused this problem. The DDM senses the ignition status on that yellow wire and sends that information through the network data line to the mirrors, sunroof and windows. If the ignition signal is lost to the DDM, as in this case, it can’t communicate that information to the other modules in its network and those accessories don’t operate.