What Does B1644 Mean?
This code indicates that the Body Control Module (BCM) has detected an open circuit in the passenger side right mirror control circuit. An open circuit means there is a break in electrical continuity preventing current flow to operate the mirror adjustment motors or heating elements. The BCM monitors the mirror circuit and sets this code when it cannot complete the electrical path through the passenger mirror assembly.
Common Causes
40%
Broken or damaged wiring in the door harness between the BCM and passenger mirror, often caused by repeated door opening/closing flexing the wires
30%
Faulty passenger side mirror assembly with internal open circuit in motor or heating element
20%
Corroded or loose connector at the passenger mirror or BCM causing intermittent or complete loss of contact
10%
Failed Body Control Module with internal circuit fault in mirror control output
Diagnostic Steps
1
Step 1: Perform visual inspection of the passenger mirror wiring harness in the door jamb area and rubber boot for visible damage, chafing, or broken wires. Check all connectors for corrosion, pushed-out pins, or moisture intrusion.
2
Step 2: Using a multimeter, backprobe the passenger mirror connector and check for battery voltage and ground on the appropriate pins while commanding mirror movement through the scan tool active test function. Verify power and ground circuits are present.
3
Step 3: If power and ground are present at the mirror connector, disconnect the mirror and measure resistance across the mirror motor terminals (typically 5-50 ohms depending on manufacturer). If open circuit (infinite resistance), replace the mirror assembly.
4
Step 4: If no power at mirror connector, trace wiring back toward BCM checking continuity on each circuit. Pay special attention to the door jamb area where wires flex. Repair or replace damaged wiring as needed.
5
Step 5: If all wiring tests good and mirror has proper resistance, check BCM connector for corrosion or terminal damage. If connector is good, suspect BCM internal fault and consider BCM replacement after verifying with manufacturer-specific diagnostics.
6
Step 6: After repair, clear codes, cycle mirror through all adjustment positions using switch, and verify code does not return. Test mirror heater function if equipped.
Estimated Repair Cost
$75 - $650
Parts + labor, varies by vehicle and location
This code indicates that the Body Control Module (BCM) has detected an open circuit in the passenger side right mirror control circuit. An open circuit means there is a break in electrical continuity preventing current flow to operate the mirror adjustment motors or heating elements. The BCM monitor...
The most common cause of B1644 (Mirror Passenger Right Circuit Open) is: Broken or damaged wiring in the door harness between the BCM and passenger mirror, often caused by repeated door opening/closing flexing the wires
Typical repair costs for B1644 range from $75 to $650, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive with this fault as it only affects mirror adjustment convenience. The mirror can typically still be adjusted manually, though proper mirror positioning is important for safe lane changes and backing up.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1644 to identify the root cause.
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Quick Info
Category
Body
System
Body Control System - Power Mirror
Difficulty
Type
Manufacturer
Recommended Tools
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