What Does B1746 Mean?
This code indicates the Body Control Module (BCM) has detected an open circuit in the passenger side mirror horizontal (left/right) adjustment switch circuit. The BCM monitors the switch inputs and has determined that the electrical path is incomplete, preventing proper communication between the switch and the mirror motor. This is a manufacturer-specific body system code related to power mirror operation.
Common Causes
35%
Failed or worn passenger mirror adjustment switch with internal open circuit or poor contact
30%
Damaged, corroded, or disconnected wiring harness between mirror switch and BCM or mirror motor
20%
Corroded or loose electrical connector at mirror switch, mirror assembly, or BCM
10%
Failed BCM with internal circuit fault or blown fuse in mirror control circuit
5%
Faulty mirror motor assembly causing feedback circuit open condition
Diagnostic Steps
1
Step 1: Visually inspect the mirror adjustment switch assembly and master door switch panel for physical damage, burnt contacts, or obvious defects. Test switch operation manually while monitoring live data for switch position changes.
2
Step 2: Using a digital multimeter, check for continuity and proper voltage (typically 5V reference or 12V depending on manufacturer) at the mirror switch connector when disconnected. Verify ground circuit integrity.
3
Step 3: Inspect all wiring harnesses from the door switch panel through the door jamb to the mirror assembly and BCM for breaks, chafing, water damage, or corrosion. Pay special attention to flexing points in door hinge area.
4
Step 4: Disconnect the passenger mirror connector and measure resistance across the horizontal adjustment motor terminals (typically 3-15 ohms). Check for short to ground or open circuit in mirror motor windings.
5
Step 5: Back-probe the BCM connector at the mirror switch circuit pins with a multimeter while operating the switch to verify signal transmission to the BCM. Compare readings to manufacturer specifications.
6
Step 6: After repairs, clear codes, perform mirror relearn procedure if required, and cycle the mirror adjustment through full range of motion in all directions to confirm proper operation and verify no code returns.
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
This code indicates the Body Control Module (BCM) has detected an open circuit in the passenger side mirror horizontal (left/right) adjustment switch circuit. The BCM monitors the switch inputs and has determined that the electrical path is incomplete, preventing proper communication between the swi...
The most common cause of B1746 (Mirror Passenger Horizontal Switch Circuit Open) is: Failed or worn passenger mirror adjustment switch with internal open circuit or poor contact
Typical repair costs for B1746 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 passenger mirror adjustment convenience feature and does not impact vehicle operation or safety systems. Repair at convenience, though proper mirror adjustment is important for visibility and safety.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1746 to identify the root cause.
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Quick Info
Category
Body
System
Power Mirror Control System (Body Electrical)
Difficulty
Type
Manufacturer
Recommended Tools
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