What Does B1810 Mean?
B1810 indicates the Body Control Module (BCM) has detected a circuit fault in the backup lamp switch input signal. This switch, typically located on the transmission or gear selector, is responsible for activating the reverse lights when the vehicle is shifted into reverse gear. The BCM has identified an abnormal voltage, open circuit, short circuit, or loss of communication from this switch circuit.
Common Causes
35%
Faulty backup lamp switch on transmission or gear selector assembly
30%
Damaged, corroded, or disconnected wiring harness between backup lamp switch and BCM
20%
Corroded or loose electrical connector at backup lamp switch or BCM
10%
Failed Body Control Module (BCM) input circuit
5%
Blown fuse or failed relay in backup lamp circuit
Diagnostic Steps
1
Step 1: Perform visual inspection of the backup lamp switch located on the transmission or gear selector. Check for physical damage, oil/fluid contamination, and verify connector is fully seated with no corrosion on terminals.
2
Step 2: Using a digital multimeter, backprobe the backup lamp switch connector with ignition ON and shift selector in Park. Check for proper reference voltage (typically 5V or 12V depending on manufacturer). Then shift to Reverse and verify voltage drop or signal change according to manufacturer specifications.
3
Step 3: Check continuity of wiring harness between backup lamp switch and BCM connector using wiring diagram. Test for opens, shorts to ground, and shorts to power. Pay special attention to areas where harness flexes near transmission or passes through body grommets.
4
Step 4: If wiring and voltage supply are correct, connect a scan tool and monitor backup lamp switch status in BCM live data while cycling shifter between Park and Reverse. Compare switch state to actual gear position to isolate switch vs BCM input failure.
5
Step 5: If all circuits test normal but code persists, perform resistance test of backup lamp switch in both Park and Reverse positions. Compare readings to manufacturer specifications (typically open circuit in forward gears, closed circuit in reverse).
6
Step 6: Clear codes, perform relearn procedure if required by manufacturer, test drive with shifts into reverse, and verify code does not return and backup lamps function properly.
Estimated Repair Cost
$75 - $350
Parts + labor, varies by vehicle and location
B1810 indicates the Body Control Module (BCM) has detected a circuit fault in the backup lamp switch input signal. This switch, typically located on the transmission or gear selector, is responsible for activating the reverse lights when the vehicle is shifted into reverse gear. The BCM has identifi...
The most common cause of B1810 (Lamp Backup Switch Input Circuit Failure) is: Faulty backup lamp switch on transmission or gear selector assembly
Typical repair costs for B1810 range from $75 to $350, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle is safe to drive, but backup lamps may not illuminate when in reverse, creating a safety hazard for other drivers and pedestrians. This also constitutes a traffic violation in most jurisdictions. Repair should be completed promptly for safety and legal compliance.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B1810 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
Lighting System / Body Control
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
A quality scan tool helps you read codes, view live data, and clear faults.
