B1640 – Mirror Passenger Left Circuit Open

The ODBII code B1640 indicates that there is an open circuit in the passenger side left mirror, meaning the electrical connection to that mirror is interrupted or not functioning properly.

The severity of ODBII code B1640 is generally considered moderate.

Common Causes For: B1639 Mirror Passenger Left Circuit Failure

• Open circuit in the wiring harness
• Faulty passenger side mirror switch
• Defective passenger side mirror assembly
• Poor ground connection
• Damaged or corroded connectors
• Blown fuse related to the mirror circuit
• Faulty body control module (BCM)

Common misdiagnosis for B1640 Mirror Passenger Left Circuit Open

• Faulty passenger side mirror
• Wiring issues in the mirror circuit
• Malfunctioning body control module (BCM)
• Defective switch or control for the mirror
• Issues with the vehicle’s electrical system
• Faulty connectors or terminals in the circuit
• Problems with the door module or assembly

Common Troubleshooting Steps

The OBD-II code B1640 indicates a problem with the passenger side mirror circuit, specifically that the circuit is open. This can be caused by various issues, including wiring problems, a faulty mirror assembly, or issues with the vehicle’s body control module (BCM). Here are some common troubleshooting steps to diagnose and resolve the B1640 code:

• Visual Inspection: **Check Wiring and Connectors: Inspect the wiring harness and connectors leading to the passenger side mirror for any signs of damage, corrosion, or loose connections.
• **Look for Shorts or Breaks: Look for any frayed wires or breaks in the insulation that could cause an open circuit.
• Test the Mirror Assembly: **Functionality Check: If possible, test the passenger side mirror’s functions (adjustment, heating, etc.) to see if they work. If the mirror is not functioning at all, it may need to be replaced.
• **Check for Water Damage: If the vehicle has been exposed to water, check for moisture in the mirror assembly or connectors.
• Use a Multimeter: **Check Voltage: With the ignition on, use a multimeter to check for voltage at the mirror connector. If there is no voltage, the issue may be upstream in the wiring or BCM.
• **Continuity Test: Perform a continuity test on the wires leading to the mirror to ensure there are no breaks in the circuit.
• Inspect the Body Control Module (BCM): **Check for Faulty BCM: If the wiring and mirror assembly are in good condition, the BCM may be at fault. Check for any other related codes that may indicate a BCM issue.
• **Reprogram or Replace: If the BCM is determined to be faulty, it may need to be reprogrammed or replaced.
• 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.
• Consult Wiring Diagrams: If the issue persists, consult the vehicle’s wiring diagrams to trace the circuit and identify any other components that may be involved.
• Professional Diagnosis: If you are unable to resolve the issue after these steps, consider seeking help from a professional mechanic or automotive technician who has experience with electrical systems. By following these troubleshooting steps, you should be able to identify and resolve the issue causing the B1640 code.