What Does B1645 Mean?
This code indicates the Body Control Module (BCM) has detected a short to battery voltage in the passenger side right mirror control circuit. This means one or more wires in the mirror circuit are receiving constant battery voltage when they should not be, causing unintended current flow. The BCM monitors mirror circuits for proper voltage levels and sets this code when it detects voltage above expected parameters in the passenger mirror control system.
Common Causes
45%
Damaged or chafed wiring in door jamb area causing short to power wire
30%
Failed passenger mirror motor or actuator with internal short to power
15%
Water intrusion in mirror housing causing corrosion and electrical bridging
10%
Failed BCM internal circuit or relay stuck closed providing constant power
Diagnostic Steps
1
Step 1: Perform visual inspection of passenger mirror wiring harness in door jamb area where repeated opening/closing causes wear, checking for exposed copper, melted insulation, or signs of shorting to adjacent power wires
2
Step 2: Disconnect passenger mirror electrical connector at the mirror assembly and measure voltage at BCM side connector pins using digital multimeter - should read 0V with ignition off and proper control voltage (typically 0-12V variable) during mirror switch operation
3
Step 3: With mirror disconnected, check resistance of mirror motor windings to ground and to B+ - readings should show proper isolation (typically >10K ohms); low resistance indicates internal mirror motor short
4
Step 4: If wiring and mirror test good, inspect mirror connector terminals and housing for water intrusion, corrosion, or pin-to-pin bridging; clean or replace connector as needed
5
Step 5: Reconnect all components, clear codes, and cycle mirror through all positions while monitoring live data for proper current draw (typically 2-5 amps during movement); verify code does not return and mirror operates normally
Estimated Repair Cost
$100 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected a short to battery voltage in the passenger side right mirror control circuit. This means one or more wires in the mirror circuit are receiving constant battery voltage when they should not be, causing unintended current flow. The BCM mo...
The most common cause of B1645 (Mirror Passenger Right Circuit Short To Battery) is: Damaged or chafed wiring in door jamb area causing short to power wire
Typical repair costs for B1645 range from $100 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to continue driving as this affects only the power mirror adjustment function and does not impact vehicle operation or safety systems. Repair at convenience to restore full mirror functionality, though prolonged short circuit could potentially drain battery or damage BCM over time.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1645 to identify the root cause.
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Quick Info
Category
Body
System
Body Control and Mirror System
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
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