What Does B1733 Mean?
B1733 indicates the Body Control Module (BCM) has detected an electrical fault in the driver's side mirror vertical adjustment switch circuit. This code is set when the BCM detects an open circuit, short to ground, short to power, or abnormal resistance in the switch or its wiring that controls up/down movement of the driver's mirror. The system has identified a communication or signal integrity problem preventing proper mirror adjustment functionality.
Common Causes
45%
Faulty driver's side mirror vertical adjustment switch with internal contact wear, corrosion, or failure
30%
Damaged, chafed, or broken wiring between the door switch panel and BCM, often in door hinge area from repeated flexing
15%
Corroded or loose electrical connector at the mirror switch or BCM causing intermittent or high resistance connection
10%
Failed Body Control Module internal circuit or driver for mirror switch input
Diagnostic Steps
1
Step 1: Perform visual inspection of driver's door mirror switch assembly for physical damage, stuck buttons, or signs of liquid intrusion. Test switch operation manually while observing for binding or abnormal feel.
2
Step 2: Using a digital multimeter, backprobe the mirror switch connector while operating the vertical adjustment switch through all positions. Verify proper resistance values and continuity per manufacturer specifications (typically 0-5 ohms closed, infinite ohms open).
3
Step 3: Inspect wiring harness from door switch panel through door hinge area into door jamb for chafing, breaks, or pinched wires. Check all related connectors for corrosion, bent pins, or moisture contamination. Repair or replace damaged wiring as needed.
4
Step 4: With ignition on and multimeter connected, monitor voltage at switch connector. Verify BCM is supplying proper reference voltage (typically 5V or 12V depending on manufacturer). Check ground circuit for less than 0.5 ohms resistance to chassis ground.
5
Step 5: If wiring and voltage supply are correct, substitute known-good mirror switch assembly and retest. Clear codes and verify proper mirror operation in all directions to confirm repair.
6
Step 6: If fault persists after switch and wiring verification, perform BCM diagnostic test routines per manufacturer service information to isolate internal module failure. Replace BCM only after all other components are confirmed functional.
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
B1733 indicates the Body Control Module (BCM) has detected an electrical fault in the driver's side mirror vertical adjustment switch circuit. This code is set when the BCM detects an open circuit, short to ground, short to power, or abnormal resistance in the switch or its wiring that controls up/d...
The most common cause of B1733 (Mirror Driver Vertical Switch Circuit Failure) is: Faulty driver's side mirror vertical adjustment switch with internal contact wear, corrosion, or failure
Typical repair costs for B1733 range from $75 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This code does not affect vehicle safety or driveability and the vehicle is safe to operate normally. The only impact is reduced convenience with manual mirror adjustment capability being compromised, though mirrors can typically still be adjusted horizontally or manually folded if needed.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1733 to identify the root cause.
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Quick Info
Category
Body
System
Body Control and Accessories
Difficulty
Type
Manufacturer
Recommended Tools
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