B1810: Backup Lamp Switch Circuit Malfunction
The B1810 code indicates a fault in the backup lamp switch input circuit. This circuit detects when the vehicle is in reverse to activate the backup lights. The control module detects an abnormal, missing, or out-of-range signal on the switch input circuit, preventing proper operation of the reverse lights or sending an incorrect signal to the vehicle's control systems. The backup lamp switch is typically mounted on the manual transmission or integrated with the shift position sensor on automatic transmissions. This fault can affect not only exterior lighting but also auxiliary systems that rely on the reverse signal, such as parking sensors or rearview camera displays.
1. Commonly Affected Makes
2. Most Common Causes
- Worn or damaged backup lamp switch
- Open, shorted, or high-resistance wiring in the switch circuit
- Corroded, loose, or disconnected switch connector
- Blown fuse for the backup lamp circuit
- Faulty body control module (BCM) or related control module
- Mechanical issue with the switch mounting on the transmission
3. Symptoms You Will Notice
- Backup lights do not illuminate when shifting into reverse
- Backup lights stay on constantly or operate intermittently
- Parking sensors or rearview camera malfunction or fail to activate in reverse
4. Step-by-Step Diagnosis
Check the backup lamp fuse and replace if blown.
Inspect the backup lamp switch connector for corrosion, damage, or looseness; clean or repair as needed.
Test the backup lamp switch for continuity when the transmission is in reverse; replace if faulty.
Check wiring between the switch and BCM for opens, shorts, or high resistance; repair as necessary.
If all else is okay, test the BCM or related module for proper operation; reprogram or replace if faulty.
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is generally safe to drive, but you will lose backup lights and possibly parking sensors or rearview camera function, which can be a safety concern when reversing, especially at night or in tight spaces. It is recommended to have it repaired promptly.
How much does it cost to fix?▼
The cost can range from $50 to $200 for a switch replacement, up to $300-$500 if wiring repairs or module reprogramming are needed. Diagnostic fees may add $100-$150.