B1689 – Autolamp Delay Circuit Failure

The ODBII code B1689 indicates a malfunction in the autolamp delay circuit, which is responsible for controlling the automatic lighting system in a vehicle.

The severity of ODBII code B1689 is generally considered moderate.

Common Causes For: B1688 Lamp Dome Input Circuit Short To Ground

• Faulty autolamp control module
• Damaged wiring or connectors
• Short circuit in the autolamp circuit
• Failed headlight switch
• Malfunctioning body control module (BCM)
• Corroded or loose electrical connections
• Defective sensors (light or rain sensors)

Common misdiagnosis for B1689 Autolamp Delay Circuit Failure

• Faulty headlight switch
• Defective body control module (BCM)
• Wiring issues or shorts in the circuit
• Malfunctioning relay
• Incorrectly diagnosed battery or charging system problems
• Issues with the lighting control module
• Faulty sensors related to ambient light detection

Common Troubleshooting Steps

The OBD-II code B1689 refers to an “Autolamp Delay Circuit Failure.” This code typically indicates a problem with the automatic headlight system, which may involve the autolamp delay feature not functioning as intended. Here are some common troubleshooting steps to diagnose and potentially resolve the issue:

• Check the Vehicle’s Manual: Refer to the vehicle’s service manual for specific information related to the autolamp system and the B1689 code. This can provide insights into the wiring diagrams and component locations.
• Inspect the Fuses: Check the fuses related to the autolamp system. A blown fuse can cause the system to malfunction. Replace any blown fuses and see if the code persists.
• Examine the Wiring and Connectors: Inspect the wiring and connectors associated with the autolamp system for any signs of damage, corrosion, or loose connections. Pay special attention to the connectors at the headlight switch and the body control module (BCM).
• Test the Autolamp Sensor: If your vehicle is equipped with a light sensor, test it to ensure it is functioning correctly. A faulty sensor can prevent the autolamp system from working properly.
• Check the Headlight Switch: Test the headlight switch for proper operation. If the switch is faulty, it may not send the correct signals to the BCM.
• 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.
• Inspect the Body Control Module (BCM): The BCM controls many functions, including the autolamp feature. Check for any faults in the BCM and ensure it is receiving the correct inputs and sending the correct outputs.
• Perform a System Reset: Sometimes, clearing the code and resetting the system can resolve temporary issues. Use an OBD-II scanner to clear the code and see if it returns.
• Check for Software Updates: In some cases, a software update for the BCM or other related modules may be necessary. Check with the manufacturer or a dealership for any available updates.
• Consult a Professional: If the issue persists after performing the above steps, it may be best to consult a professional mechanic or technician who has experience with your specific vehicle make and model.Conclusion Troubleshooting the B1689 code involves a systematic approach to identify and rectify the underlying issue. Always ensure safety precautions are taken when working on electrical systems in vehicles.