The B1746 trouble code indicates a fault within the circuit controlling the horizontal movement of the passenger side exterior mirror. This code signals that the vehicle's computer, specifically the Body Control Module (BCM), has detected an open circuit in the wiring or components associated with the passenger side mirror's horizontal adjustment mechanism. Addressing this issue promptly is crucial for restoring full functionality of the mirror and ensuring safe driving conditions.
The inability to adjust the passenger side mirror horizontally can significantly impair visibility, especially during lane changes and parking maneuvers. Diagnosing and repairing the B1746 code is essential for maintaining vehicle safety and optimal driver awareness.
| Component/Aspect | Description | Possible Causes |
|---|---|---|
| Definition of B1746 | Diagnostic Trouble Code (DTC) indicating an open circuit in the passenger side mirror's horizontal adjustment switch circuit. | Wiring issues, faulty switch, mirror motor malfunction, or BCM problems. |
| Affected System | Exterior Mirror Control System (Specifically the passenger side horizontal adjustment). | Impaired visibility, difficulty adjusting the mirror, safety concerns. |
| Symptoms | Passenger side mirror unable to move horizontally, DTC B1746 stored in the BCM, potential for other mirror functions to be affected. | Inability to properly position the mirror, reduced field of view, potential accident risk. |
| Possible Causes (Detailed) | Open circuit in wiring, corroded connectors, faulty passenger side mirror switch, internal failure of the mirror motor, BCM malfunction. | Damaged wires, water intrusion, wear and tear, short circuit in the motor, software glitches in the BCM. |
| Diagnostic Tools | Multimeter, scan tool, wiring diagrams, circuit tester. | Identifying the exact location of the open circuit or faulty component. |
| Troubleshooting Steps | Visual inspection, circuit testing, switch testing, motor testing, BCM testing (if necessary). | Isolating the cause of the open circuit and verifying the functionality of individual components. |
| Common Repair Solutions | Repairing or replacing damaged wiring, cleaning or replacing corroded connectors, replacing the passenger side mirror switch, replacing the mirror motor, BCM reprogramming or replacement (rare). | Restoring proper electrical connectivity and functionality to the mirror control system. |
| Related DTCs | Other mirror control DTCs (related to vertical adjustment, heating, or driver side mirror), power window or door lock codes. | Potential underlying electrical issues affecting multiple systems. |
| Severity | Moderate - Affects driver visibility and convenience. | Reduced field of view, potential safety hazard, inconvenience. |
| Ease of Repair | Moderate - Requires electrical troubleshooting skills and access to wiring diagrams. | Time required for diagnosis and repair, complexity of the electrical system. |
| Component Location | Passenger side door, mirror housing, dashboard (switch). | Accessibility of components for testing and repair. |
| Wiring Diagram Importance | Crucial for tracing the circuit and identifying potential points of failure. | Accurate diagnosis and efficient repair. |
| BCM Role | Controls and monitors the mirror control system, stores DTCs, and provides diagnostic information. | Interface between the switch, motor, and vehicle's electrical system. |
| Connector Corrosion | A common cause of open circuits, especially in areas exposed to moisture. | Interruption of electrical flow, intermittent mirror operation. |
| Switch Resistance Testing | Using a multimeter to check the resistance of the mirror switch in different positions. | Determining if the switch is functioning correctly. |
| Motor Voltage Testing | Applying voltage directly to the mirror motor to verify its functionality. | Determining if the motor is receiving power and operating correctly. |
| DIY vs. Professional Repair | DIY possible for simple wiring repairs or switch replacement; professional repair recommended for complex electrical issues or BCM problems. | Skill level required for the repair, potential for further damage if not performed correctly. |
| Estimated Repair Cost | Varies depending on the cause and repair solution; switch replacement is typically less expensive than motor or BCM replacement. | Budgeting for the repair. |
| Preventative Maintenance | Regularly inspect wiring and connectors for damage or corrosion, avoid exposing the mirror switch to excessive moisture. | Reducing the likelihood of future electrical problems. |
Detailed Explanations
Definition of B1746: This code specifically pinpoints an interruption in the electrical circuit responsible for controlling the horizontal (left/right) movement of the passenger side exterior mirror. The vehicle's computer uses sensors to monitor the continuity of this circuit and flags the B1746 code when an open circuit (a break in the electrical path) is detected.
Affected System: The exterior mirror control system is responsible for allowing the driver to adjust the position of the side mirrors for optimal visibility. The B1746 code directly affects the passenger side mirror's horizontal adjustment, potentially impacting the driver's ability to see vehicles in the adjacent lane.
Symptoms: The most obvious symptom is the inability to adjust the passenger side mirror horizontally. The diagnostic trouble code B1746 will be stored in the BCM's memory and can be retrieved using a scan tool. In some cases, other mirror functions (vertical adjustment or heating) might also be affected if the underlying problem is a broader electrical issue.
Possible Causes (Detailed):
- Open Circuit in Wiring: A break in the wiring harness connecting the mirror switch, mirror motor, and BCM can interrupt the electrical flow. This can be caused by physical damage, rodent chews, or stress on the wires.
- Corroded Connectors: Corrosion on electrical connectors can create resistance and eventually lead to an open circuit. This is especially common in areas exposed to moisture and road salt.
- Faulty Passenger Side Mirror Switch: The switch itself could be malfunctioning, preventing the electrical signal from reaching the mirror motor. Internal damage or wear and tear can cause the switch to fail.
- Internal Failure of the Mirror Motor: The motor responsible for the horizontal movement of the mirror might be defective. This can be due to worn brushes, internal shorts, or other mechanical failures.
- BCM Malfunction: In rare cases, a problem with the BCM itself could cause the B1746 code. This is usually diagnosed after ruling out all other possible causes.
Diagnostic Tools:
- Multimeter: Used to measure voltage, current, and resistance in the electrical circuit. Essential for identifying open circuits and testing the continuity of wires.
- Scan Tool: Used to retrieve diagnostic trouble codes (DTCs) from the vehicle's computer. Provides valuable information about the nature of the problem.
- Wiring Diagrams: Detailed schematics of the vehicle's electrical system. Crucial for tracing the circuit and identifying potential points of failure.
- Circuit Tester: A simple tool used to check for the presence of voltage in a circuit. Can help quickly identify if power is reaching the mirror switch and motor.
Troubleshooting Steps:
- Visual Inspection: Carefully inspect the wiring harness, connectors, and mirror switch for any signs of damage, corrosion, or loose connections.
- Circuit Testing: Use a multimeter to test the continuity of the wiring between the mirror switch, mirror motor, and BCM. Identify any open circuits in the wiring.
- Switch Testing: Test the mirror switch using a multimeter to ensure it is functioning correctly. Check the resistance of the switch in different positions.
- Motor Testing: Apply voltage directly to the mirror motor to verify its functionality. If the motor does not respond, it may be defective.
- BCM Testing (if necessary): If all other components test good, the BCM may be the cause of the problem. This typically requires specialized diagnostic equipment and expertise.
Common Repair Solutions:
- Repairing or Replacing Damaged Wiring: Repairing or replacing any damaged sections of the wiring harness. Use proper splicing techniques and heat shrink tubing to ensure a secure and weatherproof connection.
- Cleaning or Replacing Corroded Connectors: Cleaning corroded connectors with electrical contact cleaner or replacing them entirely. Apply dielectric grease to prevent future corrosion.
- Replacing the Passenger Side Mirror Switch: Replacing the mirror switch with a new or refurbished unit. Ensure the new switch is compatible with the vehicle.
- Replacing the Mirror Motor: Replacing the mirror motor with a new or refurbished unit. This may require removing the mirror assembly from the vehicle.
- BCM Reprogramming or Replacement (rare): Reprogramming or replacing the BCM is a last resort and should only be done by a qualified technician. This requires specialized equipment and expertise.
Related DTCs: Other mirror control DTCs, such as those related to vertical adjustment, heating, or the driver side mirror, can indicate a broader electrical issue affecting the mirror control system. Also, check for power window or door lock codes, as these systems share some wiring and components.
Severity: A B1746 code is considered moderately severe. While it doesn't prevent the vehicle from operating, it does impair driver visibility and can be a safety hazard, especially during lane changes and parking maneuvers.
Ease of Repair: The ease of repair can vary depending on the cause of the open circuit. Simple wiring repairs or switch replacements can be done by a DIYer with basic electrical knowledge. More complex electrical issues or BCM problems should be handled by a professional technician.
Component Location: The passenger side mirror is located on the passenger side door. The mirror switch is typically located on the driver's side door panel or dashboard. The BCM is usually located under the dashboard or in the center console.
Wiring Diagram Importance: A wiring diagram is essential for tracing the circuit and identifying potential points of failure. It provides a visual representation of the electrical connections between the mirror switch, mirror motor, and BCM.
BCM Role: The BCM acts as the central control unit for the mirror control system. It receives signals from the mirror switch, controls the mirror motors, and monitors the circuit for faults.
Connector Corrosion: Corrosion on electrical connectors is a common cause of open circuits, especially in areas exposed to moisture and road salt. Clean or replace corroded connectors to restore proper electrical flow.
Switch Resistance Testing: Use a multimeter to check the resistance of the mirror switch in different positions. This will help determine if the switch is functioning correctly and making proper electrical connections.
Motor Voltage Testing: Apply voltage directly to the mirror motor to verify its functionality. If the motor does not respond, it may be defective.
DIY vs. Professional Repair: DIY repair is possible for simple wiring repairs or switch replacements. Professional repair is recommended for complex electrical issues or BCM problems, as these require specialized diagnostic equipment and expertise.
Estimated Repair Cost: The estimated repair cost can vary depending on the cause of the problem and the repair solution. Switch replacement is typically less expensive than motor or BCM replacement. Get a quote from a qualified mechanic before proceeding with the repair.
Preventative Maintenance: Regularly inspect wiring and connectors for damage or corrosion. Avoid exposing the mirror switch to excessive moisture. This can help reduce the likelihood of future electrical problems.
Frequently Asked Questions
What does the B1746 code mean? It means there is an open circuit in the passenger side mirror's horizontal adjustment switch circuit. This indicates a break in the electrical path preventing the mirror from moving left or right.
Can I still drive my car with a B1746 code? Yes, but it's not recommended as it impairs visibility. The passenger side mirror will not adjust horizontally, which can be a safety hazard.
How do I fix the B1746 code myself? Start by inspecting the wiring and connectors for damage or corrosion. Then, test the mirror switch and motor with a multimeter. If you find any faulty components, replace them.
Is the B1746 code serious? It's moderately serious as it affects driver visibility and could lead to an accident. Repairing it promptly is recommended.
How much will it cost to fix a B1746 code? The cost depends on the cause of the problem. A switch replacement is typically cheaper than replacing the motor or BCM.
Conclusion
The B1746 code indicates a problem with the passenger side mirror's horizontal adjustment circuit, potentially affecting visibility and safety. Thorough diagnosis and repair, starting with a visual inspection and component testing, are crucial to restoring full functionality to the mirror control system.