What Does B1642 Mean?
This code indicates the Body Control Module (BCM) has detected a short to ground condition in the electrical circuit controlling the passenger side (left in some markets) exterior mirror. The BCM monitors the mirror circuit and sets this code when it detects current flowing to ground instead of through the mirror motor or heating element. This typically occurs when damaged wiring insulation allows the positive circuit to contact vehicle ground or when internal mirror components have failed.
Common Causes
45%
Damaged or chafed wiring in the door harness between door jamb and mirror, exposing copper to ground contact
30%
Failed mirror motor assembly with internal short to ground in adjustment mechanism
15%
Water intrusion into mirror housing causing corrosion and short circuit in heating element or motor
10%
Failed BCM output driver circuit for mirror control
Diagnostic Steps
1
Step 1: Perform visual inspection of the passenger side mirror wiring harness, particularly at the door jamb flex point and mirror base connector for visible damage, chafing, pinching, or corrosion. Check for water intrusion inside mirror housing.
2
Step 2: Disconnect the passenger mirror connector and measure resistance from each mirror motor pin to ground using a digital multimeter. All circuits should read open circuit (OL) or greater than 10K ohms. Any reading below 5 ohms indicates a short to ground.
3
Step 3: If mirror tests okay, inspect door harness by disconnecting both ends and performing continuity test between each wire and ground. Flex the harness while testing to identify intermittent shorts. Pay special attention to the area where harness passes through door jamb.
4
Step 4: If wiring is intact, reconnect all connectors and use multimeter to backprobe the BCM mirror control circuit while activating mirror functions. Voltage should be present when commanded; immediate drop to zero with circuit breaker trip indicates short. If BCM shows proper voltage with mirror disconnected but shorts with mirror connected, replace mirror assembly.
5
Step 5: Clear codes, reconnect all components, cycle mirror through all adjustment positions and verify proper operation. Re-scan for codes to confirm fault is eliminated.
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected a short to ground condition in the electrical circuit controlling the passenger side (left in some markets) exterior mirror. The BCM monitors the mirror circuit and sets this code when it detects current flowing to ground instead of thro...
The most common cause of B1642 (Mirror Passenger Left Circuit Short To Ground) is: Damaged or chafed wiring in the door harness between door jamb and mirror, exposing copper to ground contact
Typical repair costs for B1642 range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving as this only affects mirror adjustment functionality and does not impact vehicle operation or safety systems. Repair at earliest convenience to restore proper mirror adjustment capability 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 B1642 to identify the root cause.
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Quick Info
Category
Body
System
Body Electrical System - Power Mirrors
Difficulty
Type
Manufacturer
Recommended Tools
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