WOMS
B code body Medium severity

B1739 Mirror Driver Horizontal Switch Circuit Short To Battery

The OBD2 code B1739 indicates a fault in the mirror driver horizontal switch circuit, specifically that there is a short circuit to the battery, which may cause the mirror adjustment function to malfunction

Definition

The OBD2 code B1739 indicates a fault in the mirror driver horizontal switch circuit, specifically that there is a short circuit to the battery, which may cause the mirror adjustment function to malfunction

Common causes

  • Shorted wiring or connectors in the mirror driver circuit
  • Faulty mirror switch or control module
  • Damaged or frayed wiring harness
  • Corrosion or poor connections in the circuit
  • Malfunctioning mirror motor or actuator
  • Incorrect installation or aftermarket modifications

Common misdiagnoses

  • Faulty mirror switch
  • Wiring harness issues
  • Shorted wiring
  • Faulty mirror motor
  • Body control module (BCM) failure
  • Incorrectly installed or damaged mirror assembly
  • Grounding issues

Troubleshooting steps

  1. 1. Check for Related Codes

    Before proceeding, check for any other diagnostic trouble codes (DTCs) that may be present. This can provide additional context for the issue

  2. 2. Inspect Wiring and Connectors

  3. 3. Visually inspect the wiring harness and connectors associated with the mirror switch. Look for signs of damage, such as frayed wires, corrosion, or loose connections

  4. 4. Pay special attention to areas where the wiring may be exposed to heat or abrasion

  5. 5. Test the Mirror Switch

  6. 6. Remove the mirror switch from the vehicle and test it for continuity using a multimeter. Check for any shorts between the switch terminals and ensure that the switch operates correctly

  7. 7. If the switch is faulty, replace it

  8. 8. Check for Short Circuits

  9. 9. Use a multimeter to check for continuity between the mirror switch circuit and the battery. A short circuit may exist if there is continuity where there shouldn't be

  10. 10. Inspect the wiring for any signs of contact with metal surfaces or other wires that could cause a short

  11. 11. Inspect the Mirror Assembly

  12. 12. If the vehicle has power mirrors, inspect the mirror assembly for any signs of damage or malfunction. A faulty motor or internal wiring issue could contribute to the problem

  13. 13. Check Ground Connections

  14. 14. Ensure that all ground connections related to the mirror switch and assembly are secure and free of corrosion. A poor ground can cause erratic behavior and trigger fault codes

  15. 15. Scan Tool Data

  16. 16. Use an OBD-II scan tool to monitor live data related to the mirror switch operation. This can help identify if the switch is receiving the correct signals and if the system is functioning as intended

  17. 17. Repair or Replace Components

  18. 18. Based on the findings from the above steps, repair any damaged wiring or connectors. Replace any faulty components, such as the mirror switch or mirror assembly

  19. 19. Clear Codes and Test Drive

  20. 20. After making repairs, clear the trouble codes using the scan tool and take the vehicle for a test drive to see if the code returns

  21. 21. If the issue persists, consult the vehicle's service manual for specific wiring diagrams and troubleshooting procedures related to the mirror switch circuit. If you are not comfortable performing these steps or if the issue remains unresolved, it may be best to consult a professional mechanic for further diagnosis and repair