What Does B1747 Mean?
This diagnostic trouble code indicates that the Body Control Module (BCM) has detected an abnormal voltage condition in the passenger side mirror horizontal adjustment switch circuit. Specifically, the circuit is showing battery voltage when it should not, indicating a short to power condition. This fault prevents proper control of the passenger mirror's left-right adjustment function.
Common Causes
40%
Damaged or chafed wiring harness causing short to power between the mirror switch and mirror motor
30%
Failed passenger mirror switch with internal short to battery voltage
20%
Faulty mirror motor or internal mirror wiring shorted to power
10%
Body Control Module internal fault causing false detection or output short
Diagnostic Steps
1
Step 1: Perform visual inspection of the passenger door wiring harness, particularly at flex points near the door hinge and mirror base, looking for damaged insulation, pinched wires, or evidence of water intrusion
2
Step 2: Disconnect the passenger mirror switch connector and check for battery voltage on the horizontal adjustment circuit wire using a digital multimeter (should read 0V with switch disconnected; presence of 12V confirms short to power upstream of switch)
3
Step 3: If voltage is present at disconnected switch, disconnect the passenger mirror assembly connector and recheck voltage at switch harness to isolate fault between switch and mirror or between BCM and switch
4
Step 4: Using a multimeter in resistance mode, check continuity between the suspect horizontal switch circuit wire and battery positive throughout the harness with all components disconnected to locate the exact short location
5
Step 5: If no external short is found, test the mirror switch itself by measuring resistance across horizontal switch terminals while actuating the switch in both directions (should show open circuit when released, closed circuit when pressed)
6
Step 6: Repair identified short or replace faulty component, reconnect all connectors, clear codes, and verify proper mirror operation in all directions while monitoring for code recurrence
Estimated Repair Cost
$100 - $450
Parts + labor, varies by vehicle and location
This diagnostic trouble code indicates that the Body Control Module (BCM) has detected an abnormal voltage condition in the passenger side mirror horizontal adjustment switch circuit. Specifically, the circuit is showing battery voltage when it should not, indicating a short to power condition. This...
The most common cause of B1747 (Mirror Passenger Horizontal Switch Circuit Short To Battery) is: Damaged or chafed wiring harness causing short to power between the mirror switch and mirror motor
Typical repair costs for B1747 range from $100 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
This fault does not affect vehicle safety or drivability and the vehicle is safe to operate normally. The only impact is loss of horizontal adjustment control for the passenger side mirror, which may inconvenience passengers but does not impair the driver's primary mirrors or visibility.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1747 to identify the root cause.
OBDHut Mobile App
Scan codes directly from your car with the OBDHut app.
Coming Soon
Quick Info
Category
Body
System
Body Control and Accessories
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
