B1631

Step 1: Perform visual inspection of driver's side mirror assembly for physical damage, water intrusion, or obvious connector issues. Check mirror operation using switch controls and note if mirror moves in any direction or is completely inoperative.

Step 2: Using a digital multimeter, check for battery voltage (12-14V) at the mirror connector with ignition on while activating the mirror switch in all directions. Verify ground circuit continuity to ensure power is reaching the mirror assembly.

Step 3: Disconnect the mirror connector and measure resistance across mirror motor terminals (typically 5-50 ohms depending on manufacturer). Infinite resistance indicates open motor windings; near-zero resistance indicates shorted motor.

Step 4: Inspect wiring harness in door jamb area for chafing, breaks, or corrosion by flexing the door open and closed while monitoring circuit continuity with multimeter. Pay special attention to the rubber boot area where wires pass through door jamb.

Step 5: If wiring and mirror motor test within specifications, perform BCM output test using scan tool active tests to command mirror movement while monitoring voltage at BCM connector. This isolates whether fault is in BCM driver circuit or downstream components.

Step 6: After repairs, clear codes, cycle mirror through full range of motion in all directions, and verify code does not return. Perform several door open/close cycles to confirm harness repair integrity.