What Does B1638 Mean?
This code indicates that the Body Control Module (BCM) has detected a short to ground in the electrical circuit controlling the right side mirror's motor driver. The circuit responsible for adjusting the passenger-side mirror position is experiencing abnormally low resistance, causing excessive current flow to ground instead of through the mirror motor. This fault prevents proper mirror adjustment and protects the control module from damage by disabling the affected circuit.
Common Causes
45%
Damaged wiring harness or chafed insulation in mirror wiring between door hinge area and mirror assembly
30%
Failed mirror motor assembly with internal short to ground in driver circuit
15%
Corroded or moisture-damaged mirror connector causing short circuit
10%
Failed Body Control Module internal mirror driver circuit
Diagnostic Steps
1
Step 1: Perform visual inspection of right mirror wiring harness from door jamb through door hinge area to mirror assembly, checking for pinched, chafed, or damaged insulation that could cause ground contact
2
Step 2: Disconnect the right mirror electrical connector and inspect for corrosion, water intrusion, bent pins, or carbon tracking. Measure resistance between mirror motor terminals and ground; should read open circuit (infinite resistance). Reading below 10k ohms indicates internal motor short
3
Step 3: With mirror disconnected, use multimeter to check resistance between BCM mirror driver circuit wire and ground at the mirror connector (BCM side). Should read open circuit; low resistance indicates wiring harness short to ground
4
Step 4: If wiring tests normal, reconnect mirror and command mirror adjustment using scan tool active test function while monitoring current draw. Excessive current (above 3-5 amps) confirms mirror motor internal short
5
Step 5: Repair or replace identified faulty component (wiring, connector, or mirror assembly), clear codes, and verify proper mirror operation in all directions with no code return
Estimated Repair Cost
$100 - $450
Parts + labor, varies by vehicle and location
This code indicates that the Body Control Module (BCM) has detected a short to ground in the electrical circuit controlling the right side mirror's motor driver. The circuit responsible for adjusting the passenger-side mirror position is experiencing abnormally low resistance, causing excessive curr...
The most common cause of B1638 (Mirror Driver Right Short To Ground) is: Damaged wiring harness or chafed insulation in mirror wiring between door hinge area and mirror assembly
Typical repair costs for B1638 range from $100 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive as this only affects mirror adjustment functionality and does not impact critical vehicle operation. Repair at convenience, though properly adjusted mirrors are important for safe lane changes and backing maneuvers.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1638 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Body
System
Body Electrical System - Power Mirror Control
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
