B1740 – Mirror Driver Horizontal Switch Circuit Short To Ground

The ODBII 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.

The severity of ODBII code B1740 is generally considered moderate.

Common Causes For: B1739 Mirror Driver Horizontal Switch Circuit Short To Battery

• 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 misdiagnosis for B1740 Mirror Driver Horizontal Switch Circuit Short To Ground

• 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

Common Troubleshooting Steps

The OBD-II code B1740 indicates a problem with the mirror driver horizontal switch circuit, specifically a short to ground. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Visual Inspection:
• Check the wiring and connectors associated with the mirror switch and the mirror itself. Look for any signs of damage, fraying, or corrosion.
• Inspect the mirror switch for any physical damage or wear.
• Check for Shorts:
• 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.
• Inspect the wiring harness for any pinched or exposed wires that could be causing a short.
• Test the Mirror Switch:
• With the switch disconnected, test the switch for proper operation using a multimeter. Check for resistance across the terminals when the switch is activated.
• If the switch is faulty, replace it.
• Inspect the Mirror Assembly:
• 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.
• Look for any signs of moisture or corrosion inside the mirror assembly that could cause a short.
• Check the Ground Connections:
• 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.
• 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.
• Repair or Replace Components:
• Based on your findings, repair any damaged wiring or connectors. If the mirror switch or mirror assembly is faulty, replace them as necessary.
• Clear Codes and Test Drive:
• 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.
• Consult Service Manual:
• If the issue persists, consult the vehicle’s service manual for specific wiring diagrams and troubleshooting procedures related to the mirror switch circuit.
• Seek Professional Help:
• 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.