The B1644 diagnostic trouble code (DTC) indicates an issue with the electrical circuit controlling the passenger side (right) side mirror. This code signals that the vehicle's computer has detected an open circuit within the mirror's control system, potentially impacting its functionality. Addressing this issue promptly is important to ensure the safety and convenience of adjusting the mirror.
B1644: Understanding the Code
| Category | Description | Possible Causes |
|---|---|---|
| Code Definition | B1644: Mirror Passenger Right Circuit Open | Broken wiring, faulty mirror motor, faulty mirror switch, corroded connectors, blown fuse, faulty body control module (BCM) |
| Affected System | Power Mirror System (Passenger Side) | Mirror adjustment (up/down, left/right), mirror heating (if equipped), turn signal (if equipped) |
| Symptoms | Passenger side mirror not adjusting, passenger side mirror heating not working, passenger side mirror turn signal not working (if equipped), DTC B1644 present | Mirror adjustment failure, warning lights on the dashboard |
| Diagnostic Tools | Multimeter, scan tool (OBD-II scanner), wiring diagram | To test the circuit for continuity, voltage, and resistance. To read the DTC and clear it after repair. |
| Common Repair Steps | Inspect wiring and connectors, test the mirror motor, test the mirror switch, check fuses, test the BCM (last resort) | Repair or replace damaged wiring, replace the mirror motor, replace the mirror switch, replace the fuse, reprogram or replace the BCM |
| Severity | Low to Medium | Reduced visibility, safety hazard, inconvenience |
| Cost to Repair | Varies widely depending on the cause, from a few dollars for a fuse to hundreds for a BCM replacement | Cost of parts + labor if professional repair is needed |
| Related Codes | B1640-B1649 (related mirror circuit codes), other body control module codes | Understanding related codes can help narrow down the issue |
| Vehicle Systems Affected | Body Control Module (BCM), Power Mirror System | The BCM controls the power mirror system |
| Location of Components | Mirror assembly, door panel, under the dashboard (BCM) | Knowing the location of the components is essential for diagnosis and repair |
Detailed Explanations
Code Definition: B1644: Mirror Passenger Right Circuit Open
This is the core definition of the diagnostic trouble code. It signifies that the vehicle's computer (typically the Body Control Module or BCM) has detected a break or interruption in the electrical circuit controlling the passenger-side power mirror. This "open" prevents the electrical current from flowing, thus preventing the mirror from functioning correctly.
Affected System: Power Mirror System (Passenger Side)
The power mirror system is the electrical and mechanical system that allows the driver to remotely adjust the position of the side mirrors. The B1644 code specifically points to a problem within the passenger-side mirror's circuit. This system might also include features like heated mirrors or turn signals integrated into the mirror housing.
Symptoms
- Passenger side mirror not adjusting: This is the most obvious symptom. The mirror will not move up, down, left, or right when the mirror adjustment controls are used.
- Passenger side mirror heating not working: If the mirror is equipped with a heating element (often used for defrosting), it may not function.
- Passenger side mirror turn signal not working (if equipped): If the mirror has an integrated turn signal, it will not illuminate.
- DTC B1644 present: The diagnostic trouble code will be stored in the vehicle's computer and can be read using an OBD-II scanner.
- Warning lights on the dashboard: Depending on the vehicle make and model, a warning light may illuminate on the dashboard to indicate a problem with the electrical system.
Diagnostic Tools
- Multimeter: A multimeter is essential for testing the electrical circuit. It can measure voltage, resistance, and continuity, which are critical for identifying breaks or shorts in the wiring.
- Scan tool (OBD-II scanner): An OBD-II scanner is needed to read the B1644 code and any other related codes stored in the vehicle's computer. Some scanners can also provide live data readings from the mirror system.
- Wiring diagram: A wiring diagram for the vehicle's power mirror system is invaluable. It shows the layout of the circuit, the location of components, and the wiring connections.
Common Repair Steps
- Inspect wiring and connectors: This is the first and often most important step. Look for any signs of damage to the wiring, such as cuts, abrasions, or corrosion. Pay close attention to the connectors that plug into the mirror motor, the mirror switch, and the BCM.
- Test the mirror motor: Use a multimeter to test the mirror motor for continuity. If the motor has an open circuit, it will need to be replaced. You can also try applying power directly to the motor to see if it functions.
- Test the mirror switch: The mirror switch controls the direction of the mirror adjustment. Use a multimeter to test the switch for proper operation. Make sure that the switch is sending the correct signals to the mirror motor.
- Check fuses: A blown fuse can also cause an open circuit. Check the fuse that protects the power mirror system. Refer to the vehicle's owner's manual for the location of the fuse.
- Test the BCM (last resort): The BCM controls many of the vehicle's electrical functions, including the power mirror system. If all other components have been tested and found to be working properly, the BCM may be faulty. This is rare and should be diagnosed by a qualified technician.
Severity
The severity of a B1644 code is generally considered low to medium. While it doesn't typically prevent the vehicle from running, it can impair visibility and be a safety hazard, especially if the driver cannot adjust the passenger-side mirror properly. The inconvenience of not having a functional mirror is also a factor.
Cost to Repair
The cost to repair a B1644 code can vary widely depending on the cause. A blown fuse may only cost a few dollars to replace. However, replacing the mirror motor, mirror switch, or BCM can be significantly more expensive. Labor costs can also add to the overall expense.
Related Codes
- B1640-B1649 (related mirror circuit codes): These codes indicate problems with other aspects of the mirror circuit, such as shorts or high resistance.
- Other body control module codes: If the BCM is faulty, other codes related to the body's electrical systems may also be present.
Vehicle Systems Affected
- Body Control Module (BCM): The BCM is the central control unit for many of the vehicle's body electrical functions, including the power mirror system.
- Power Mirror System: This system includes the mirror motor, mirror switch, wiring, and connectors that control the movement of the side mirrors.
Location of Components
- Mirror assembly: The mirror motor and heating element (if equipped) are located inside the mirror housing.
- Door panel: The mirror switch is typically located on the door panel.
- Under the dashboard (BCM): The BCM is usually located under the dashboard, often on the driver's side.
Frequently Asked Questions
What does the B1644 code mean?
It means there's an open circuit in the passenger side mirror's electrical system, preventing it from functioning properly.
Can I fix this problem myself?
Yes, if you have experience with electrical troubleshooting and access to the necessary tools (multimeter, OBD-II scanner, wiring diagram). However, professional diagnosis and repair are recommended if you are not comfortable working with electrical systems.
How much will it cost to fix?
The cost varies depending on the cause. A simple fuse replacement is cheap, but replacing the mirror motor or BCM can be more expensive.
Is it safe to drive with this code?
Driving is generally safe, but reduced visibility due to a non-adjustable mirror can be a safety hazard.
Where do I start diagnosing this problem?
Begin by visually inspecting the wiring and connectors associated with the passenger side mirror. Use a multimeter to test the circuit for continuity and voltage.
Conclusion
The B1644 code indicates a break in the electrical circuit controlling the passenger side mirror. Diagnosing and repairing this issue involves systematically checking the wiring, connectors, mirror motor, mirror switch, and potentially the BCM. Prompt attention to this code will ensure proper mirror functionality and maintain safe driving conditions.