B1735

Step 1: Visually inspect the driver's door wiring harness boot at the door jamb for pinched, damaged, or chafed wires. Flex the door open and closed while observing for wire movement or damage points.

Step 2: Disconnect the driver's mirror control switch connector and use a multimeter to measure voltage at the vertical control circuit terminal (refer to wiring diagram). Should read 0V with ignition on; if battery voltage present, fault is downstream of switch.

Step 3: Disconnect the driver's side mirror assembly connector and check for battery voltage on the vertical motor control wire with switch unplugged. If voltage disappears, switch is faulty; if voltage remains, wiring harness is shorted.

Step 4: If wiring harness shows short, carefully inspect entire run from BCM through door jamb to mirror for wire damage, particularly where harness flexes or contacts metal edges. Repair or replace affected section.

Step 5: If mirror assembly is confirmed faulty, remove mirror and inspect connector terminals and internal circuit board for water damage, corrosion, or burnt traces before replacement.

Step 6: Clear codes, reconnect all components, and cycle mirror vertical adjustment through full range while monitoring live data to confirm proper voltage signals and no code recurrence.