What Does B1641 Mean?
This diagnostic trouble code indicates that the Body Control Module (BCM) has detected an electrical short to battery voltage in the passenger side left mirror control circuit. The BCM monitors the mirror's electrical circuit and has identified that voltage is present on a circuit that should normally be controlled or at a lower voltage level. This typically occurs when a wire in the mirror circuit has come into contact with a constant 12V power source, causing unintended current flow.
Common Causes
40%
Damaged or chafed wiring harness in the door jamb area where wires flex during door operation
30%
Failed mirror motor or internal mirror switch assembly with internal short circuit
20%
Moisture intrusion or corrosion in mirror connector causing cross-circuit contact
10%
Faulty Body Control Module with internal circuit failure on mirror control output
Diagnostic Steps
1
Step 1: Perform a thorough visual inspection of the passenger side mirror wiring harness, particularly in the door jamb area where the harness flexes. Look for chafed insulation, pinched wires, or damage. Check mirror connector for corrosion, moisture, or bent pins.
2
Step 2: Disconnect the passenger side mirror connector and use a digital multimeter to measure voltage on the mirror control circuit wires at the vehicle harness side with ignition on. Reading should be 0V or minimal control voltage; presence of 12V indicates a short to battery upstream of the connector.
3
Step 3: If voltage is present at the harness connector, disconnect the BCM connector and check for continuity between the affected mirror circuit wire and any known battery voltage sources. Resistance should be infinite (open circuit); low resistance confirms a short in the harness between BCM and mirror.
4
Step 4: If no voltage is found at the harness side with mirror disconnected, reconnect the mirror and measure current draw on the circuit. Excessive current indicates internal mirror motor or switch short. Replace mirror assembly if confirmed.
5
Step 5: Repair or replace any damaged wiring harness sections, clean and seal connectors if corrosion is found, or replace the mirror assembly if internal short is confirmed. Clear codes and verify proper mirror operation in all directions with no code return.
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
This diagnostic trouble code indicates that the Body Control Module (BCM) has detected an electrical short to battery voltage in the passenger side left mirror control circuit. The BCM monitors the mirror's electrical circuit and has identified that voltage is present on a circuit that should normal...
The most common cause of B1641 (Mirror Passenger Left Circuit Short To Battery) is: Damaged or chafed wiring harness in the door jamb area where wires flex during door operation
Typical repair costs for B1641 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 power mirror adjustment functionality. The mirror can still be adjusted manually if needed. Repair at convenience, though addressing electrical shorts promptly prevents potential drain on the battery or further electrical system damage.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1641 to identify the root cause.
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Quick Info
Category
Body
System
Body Electrical System - Mirror Control
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
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