What Does B1737 Mean?
This code indicates the Body Control Module (BCM) has detected an electrical fault in the driver's side power mirror horizontal adjustment switch circuit. The BCM monitors the switch input signals and has identified an open circuit, short to ground, short to power, or abnormal resistance in the horizontal position control switch wiring or switch itself. This prevents proper left-right adjustment of the driver's side mirror.
Common Causes
45%
Faulty driver's door mirror control switch assembly with internal contact failure or corrosion
30%
Damaged or corroded wiring/connector between mirror switch and BCM in driver's door harness
15%
Broken or shorted wire in driver's door between hinge and door panel due to flexing fatigue
10%
Failed Body Control Module with internal switch input circuit damage
Diagnostic Steps
1
Step 1: Perform visual inspection of mirror control switch assembly and connector for obvious damage, corrosion, moisture intrusion, or loose pins. Check switch for proper physical operation and tactile feedback.
2
Step 2: Using a digital multimeter, backprobe the mirror switch connector and verify proper voltage supply (typically 5V or 12V reference) and ground continuity at the switch terminals with ignition on.
3
Step 3: Test the horizontal switch circuit resistance by measuring across the appropriate switch terminals while actuating the switch left and right. Compare readings to manufacturer specifications (typically 0-5 ohms when activated, infinite when released).
4
Step 4: Inspect driver's door wiring harness in the hinge area for wire breakage, chafing, or pinching. Flex the harness while monitoring circuit continuity with multimeter to identify intermittent opens.
5
Step 5: If all wiring and switch test normal, verify BCM is receiving proper signals by accessing BCM data stream and observing mirror switch input status while actuating horizontal control.
6
Step 6: Replace faulty component (switch, repair wiring, or BCM if confirmed defective), clear codes, and verify mirror horizontal operation functions properly in both directions without code return.
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected an electrical fault in the driver's side power mirror horizontal adjustment switch circuit. The BCM monitors the switch input signals and has identified an open circuit, short to ground, short to power, or abnormal resistance in the hori...
The most common cause of B1737 (Mirror Driver Horizontal Switch Circuit Failure) is: Faulty driver's door mirror control switch assembly with internal contact failure or corrosion
Typical repair costs for B1737 range from $75 to $450, 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 convenience. This does not impact vehicle operation or safety systems, though proper mirror positioning is important for visibility and safe lane changes.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1737 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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