B1740: Mirror Driver Horizontal Switch Circuit Short To Ground

Definition

The OBD2 code B1740 indicates a fault in the mirror driver horizontal switch circuit, specifically that there is a short to ground, which means the circuit is unintentionally connected to the ground, causing improper operation of the mirror adjustment function

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

Common misdiagnoses

Faulty mirror switch
Wiring harness issues
Shorted wiring
Faulty mirror motor
Body control module (BCM) malfunction
Incorrectly installed or damaged mirror assembly
Grounding issues in the electrical system

Troubleshooting steps

1. Visual Inspection
2. Check the wiring and connectors associated with the mirror switch and the mirror itself. Look for any signs of damage, fraying, or corrosion
3. Inspect the mirror switch for any physical damage or wear
4. Check for Shorts
5. Use a multimeter to check for continuity in the wiring harness. Disconnect the mirror switch and check for continuity between the switch terminals and ground. A short to ground will show continuity where it shouldn't exist
6. Inspect the wiring harness for any pinched or exposed wires that could be causing a short
7. Test the Mirror Switch
8. With the switch disconnected, test the switch for proper operation using a multimeter. Check for resistance across the terminals when the switch is activated
9. If the switch is faulty, replace it
10. Inspect the Mirror Assembly
11. If the vehicle has powered mirrors, check the mirror assembly for any internal shorts. This may require disassembling the mirror to inspect the motor and wiring
12. Look for any signs of moisture or corrosion inside the mirror assembly that could cause a short
13. Check the Ground Connections
14. Ensure that all ground connections related to the mirror switch and mirror assembly are clean and secure. A poor ground can sometimes cause erratic behavior
15. Scan for Additional Codes
16. Use an OBD-II scanner to check for any additional trouble codes that may provide more context or indicate related issues
17. Repair or Replace Components
18. Based on your findings, repair any damaged wiring or connectors. If the mirror switch or mirror assembly is faulty, replace them as necessary
19. Clear Codes and Test Drive
20. After making repairs, clear the trouble codes using an OBD-II scanner and take the vehicle for a test drive to see if the code returns
21. If the issue persists, consult the vehicle's service manual for specific wiring diagrams and troubleshooting procedures related to the mirror switch circuit
22. Seek Professional Help
23. If you are unable to resolve the issue, consider seeking assistance from a professional mechanic or automotive technician who has experience with electrical systems. By following these steps, you should be able to identify and resolve the issue causing the B1740 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Visual Inspection

2. Check the wiring and connectors associated with the mirror switch and the mirror itself. Look for any signs of damage, fraying, or corrosion

3. Inspect the mirror switch for any physical damage or wear

4. Check for Shorts

5. Use a multimeter to check for continuity in the wiring harness. Disconnect the mirror switch and check for continuity between the switch terminals and ground. A short to ground will show continuity where it shouldn't exist

6. Inspect the wiring harness for any pinched or exposed wires that could be causing a short

7. Test the Mirror Switch

8. With the switch disconnected, test the switch for proper operation using a multimeter. Check for resistance across the terminals when the switch is activated

9. If the switch is faulty, replace it

10. Inspect the Mirror Assembly

11. If the vehicle has powered mirrors, check the mirror assembly for any internal shorts. This may require disassembling the mirror to inspect the motor and wiring

12. Look for any signs of moisture or corrosion inside the mirror assembly that could cause a short

13. Check the Ground Connections

14. Ensure that all ground connections related to the mirror switch and mirror assembly are clean and secure. A poor ground can sometimes cause erratic behavior

15. Scan for Additional Codes

16. Use an OBD-II scanner to check for any additional trouble codes that may provide more context or indicate related issues

17. Repair or Replace Components

18. Based on your findings, repair any damaged wiring or connectors. If the mirror switch or mirror assembly is faulty, replace them as necessary

19. Clear Codes and Test Drive

20. After making repairs, clear the trouble codes using an OBD-II scanner and take the vehicle for a test drive to see if the code returns

21. If the issue persists, consult the vehicle's service manual for specific wiring diagrams and troubleshooting procedures related to the mirror switch circuit

22. Seek Professional Help

23. If you are unable to resolve the issue, consider seeking assistance from a professional mechanic or automotive technician who has experience with electrical systems. By following these steps, you should be able to identify and resolve the issue causing the B1740 code