B1811 – Lamp Backup Switch Input Circuit Open

The ODBII code B1811 indicates that there is an open circuit in the backup lamp switch input, meaning the vehicle’s system is not receiving a signal from the backup lamp switch when it should.

The severity of ODBII code B1811 is generally considered moderate.

Common Causes For: B1810 Lamp Backup Switch Input Circuit Failure

• Faulty backup lamp switch
• Open circuit in wiring
• Corroded or damaged connectors
• Blown fuse
• Faulty body control module (BCM)
• Poor ground connection

Common misdiagnosis for B1811 Lamp Backup Switch Input Circuit Open

• Faulty backup lamp switch
• Wiring issues or shorts in the circuit
• Defective body control module (BCM)
• Malfunctioning reverse light bulbs
• Poor ground connections
• Issues with the transmission range sensor
• Faulty connectors or terminals in the circuit

Common Troubleshooting Steps

The OBD-II code B1811 indicates a problem with the backup lamp switch input circuit, specifically that the circuit is open. This can affect the operation of the backup lights and may also trigger other related issues. Here are some common troubleshooting steps to diagnose and resolve the B1811 code:

• Check the Vehicle’s Manual: Refer to the vehicle’s service manual for specific information regarding the backup lamp switch and circuit layout.
• Visual Inspection: Inspect the wiring and connectors associated with the backup lamp switch. Look for any signs of damage, corrosion, or loose connections.
• Check the backup lamp switch itself for physical damage or wear.
• Test the Backup Lamp Switch: Use a multimeter to test the continuity of the backup lamp switch. It should show continuity when the switch is activated (in reverse).
• If the switch is faulty, replace it.
• Check the Circuit: Inspect the wiring harness for any breaks or shorts. Use a multimeter to check for continuity in the circuit.
• Ensure that there are no open circuits or shorts to ground.
• Inspect the Backup Lights: Check the backup lights themselves to ensure they are functioning properly. Replace any burnt-out bulbs.
• Verify that the backup lights are receiving power when the vehicle is in reverse.
• Check Fuses: Inspect the fuses related to the backup lights and the backup lamp switch circuit. Replace any blown fuses.
• Scan for Additional Codes: Use an OBD-II scanner to check for any additional trouble codes that may provide more context or indicate related issues.
• Clear the Code: After performing repairs, clear the trouble code using an OBD-II scanner and take the vehicle for a test drive to see if the code returns.
• Consult a Professional: If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician for further diagnosis.Additional Tips: – Always ensure the vehicle is in a safe position and the ignition is off before working on electrical components. – If you’re not comfortable performing these checks, it’s advisable to seek professional help to avoid further damage or safety issues. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the B1811 code.