B1736

Step 1: Perform visual inspection of the driver's door wiring harness, focusing on the hinge area where wires flex during door operation. Look for chafed insulation, pinched wires, or visible damage. Check all connectors for corrosion, moisture intrusion, or pushed-out pins.

Step 2: Disconnect the mirror control switch connector and measure resistance between the vertical switch circuit terminal (consult wiring diagram for pin identification) and chassis ground using a digital multimeter. Reading should be open circuit (OL/infinite resistance); any measurable resistance indicates a short to ground in the harness.

Step 3: If harness tests good, inspect the mirror switch itself by measuring resistance across the vertical adjustment switch terminals with the switch disconnected. Actuate the switch through all positions while monitoring resistance; any direct ground path when not in the appropriate switch position indicates internal switch failure.

Step 4: Check BCM connector terminals for corrosion or damage and verify proper pin seating. If all external components and wiring test normal, suspect BCM internal circuit fault. Perform BCM power and ground verification before replacement.

Step 5: After repair, clear codes, operate the mirror vertical adjustment through full range of motion multiple times, and verify no code returns. Flex the door through full open/close cycles to ensure repair holds under movement stress.