B1347 – Heated Backlite Relay Circuit Failure

The ODBII code B1347 indicates a failure in the heated backlite relay circuit, which is responsible for controlling the rear window defroster.

The severity of ODBII code B1347 is generally considered moderate.

Common Causes For: B1346 Heated Backlite Input Circuit Short To Battery

• Faulty heated backlite relay
• Damaged wiring or connectors in the relay circuit
• Short circuit in the heated backlite circuit
• Open circuit in the heated backlite circuit
• Faulty heated backlite switch
• Malfunctioning body control module (BCM)
• Corrosion or poor connections in the relay or circuit components

Common misdiagnosis for B1347 Heated Backlite Relay Circuit Failure

• Faulty heated backlite switch
• Defective body control module (BCM)
• Wiring issues or shorts in the circuit
• Malfunctioning relay
• Faulty heated backlite element
• Incorrectly diagnosed as a general electrical issue
• Misinterpretation of other related codes
• Battery or charging system problems

Common Troubleshooting Steps

The OBD-II code B1347 indicates a “Heated Backlite Relay Circuit Failure.” This code is typically associated with issues in the heated rear window or backlite system. Here are some common troubleshooting steps to diagnose and resolve the issue:

• Check the Vehicle’s Manual: Refer to the vehicle’s service manual for specific information regarding the heated backlite system and the relay circuit.
• Visual Inspection: Inspect the wiring and connectors associated with the heated backlite relay for any signs of damage, corrosion, or loose connections.
• Check the heated backlite itself for any cracks or damage.
• Test the Relay: Locate the heated backlite relay in the fuse box or relay panel.
• Remove the relay and test it using a multimeter to ensure it is functioning properly. You can also swap it with a similar relay (if available) to see if the issue persists.
• Check Fuses: Inspect the fuses related to the heated backlite circuit. Replace any blown fuses and check if the problem is resolved.
• Test the Heated Backlite: Use a multimeter to check for continuity in the heated backlite element. If there is no continuity, the element may be faulty and needs replacement.
• Check for Power and Ground: Use a multimeter to check for power at the relay and the heated backlite circuit when the system is activated. Ensure that the relay is receiving power and that the ground connection is solid.
• 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 Control Module: If all other components check out, the issue may lie within the control module that manages the heated backlite system. Inspect for any faults or failures in the module.
• Consult a Professional: If you are unable to diagnose or resolve the issue after these steps, it may be best to consult a professional mechanic or technician who has experience with your specific vehicle model.
• Clear Codes and Test Drive: After performing repairs, clear the trouble codes using an OBD-II scanner and take the vehicle for a test drive to see if the code returns. By following these steps, you should be able to identify and resolve the issue related to the B1347 code. Always ensure safety precautions are taken when working on electrical systems in vehicles.