The B1779 diagnostic trouble code (DTC) indicates an issue within the electrical circuit controlling the downward movement of a vehicle's side mirror. This code signifies that the vehicle's computer (typically the Body Control Module or BCM) has detected an open circuit in the wiring or components associated with the mirror's downward adjustment function. Addressing this issue promptly is crucial for maintaining safe vehicle operation, as it can impact visibility and maneuverability.
This article delves into the specifics of the B1779 code, exploring its causes, symptoms, diagnostic procedures, and potential solutions. We'll provide a comprehensive guide to help you understand and address this problem effectively.
| Topic | Description | Potential Solutions |
|---|---|---|
| Definition of B1779 | Mirror Driver Down Circuit Open – Indicates an open circuit in the wiring or components controlling the downward movement of a side mirror. | N/A |
| Affected System | Power Mirror System – Specifically the circuit responsible for the downward adjustment of one or both mirrors. | N/A |
| Common Symptoms | Mirror fails to move downward when the control is activated. Other mirror functions (up, left, right) may still work. | N/A |
| Possible Causes | - Open circuit in the wiring harness to the mirror. - Faulty mirror switch. - Defective mirror motor. - Corroded or loose connectors. - Faulty Body Control Module (BCM). - Blown fuse (less common, but possible). | N/A |
| Diagnostic Tools | - Multimeter. - Wiring diagram specific to the vehicle. - Scan tool (for reading and clearing codes, and potentially accessing BCM data). | N/A |
| Diagnostic Steps | 1. Visually inspect wiring and connectors. 2. Test the mirror switch. 3. Check the mirror motor. 4. Test the wiring harness. 5. Check the BCM (last resort). | N/A |
| Wiring Inspection Points | - Connector at the mirror assembly. - Connector at the mirror switch. - Wiring harness between the switch and the mirror. - Ground connections. | N/A |
| Mirror Switch Testing | - Use a multimeter to check for continuity when the switch is in the "down" position. Refer to wiring diagram for specific pin locations. | N/A |
| Mirror Motor Testing | - Directly apply voltage to the motor to see if it moves. Refer to wiring diagram for correct polarity. | N/A |
| BCM Involvement | - The BCM controls the power mirror system. A faulty BCM can incorrectly report or cause open circuits. | N/A |
| Fuse Location | - Consult the vehicle's owner's manual for the location of the fuse(s) related to the power mirror system. | N/A |
| Repair Strategies | - Repair or replace damaged wiring. - Replace faulty connectors. - Replace the mirror switch. - Replace the mirror motor. - Replace the BCM (if diagnosed as faulty). | N/A |
| Related DTCs | B1778 (Mirror Driver Up Circuit Open), B1780 (Mirror Driver Left Circuit Open), B1781 (Mirror Driver Right Circuit Open). | N/A |
| Impact on Safety | Reduced visibility and maneuverability due to the inability to adjust the mirror downward. | N/A |
| Estimated Repair Costs | Varies widely depending on the cause. Wiring repair may be inexpensive, while BCM replacement can be costly. | N/A |
| Difficulty Level | Moderate to High. Requires electrical troubleshooting skills and access to wiring diagrams. | N/A |
| Tools Required | Multimeter, Wire Strippers, Wire Connectors, Socket Set, Screwdrivers, Wiring Diagram. | N/A |
| Component Locations | - Mirror Switch: Typically located on the door panel. - Mirror Motor: Inside the mirror housing. - BCM: Usually located under the dashboard. | N/A |
| Voltage Range | Typically 12V DC for power mirror systems. | N/A |
| Ground Point | Check the ground point for the power mirror system to ensure it is clean and secure. | N/A |
| Connector Types | Multi-pin connectors are commonly used for mirror wiring. Look for corrosion or damage. | N/A |
| Wiring Color Codes | Refer to the vehicle-specific wiring diagram for accurate color codes. | N/A |
| Mirror Types | Manual, Electric, Heated, Auto-Dimming, Power Folding. The B1779 code specifically applies to electric power mirrors. | N/A |
| OEM vs. Aftermarket | OEM parts are generally recommended for critical components like the BCM, but aftermarket mirror motors and switches may be acceptable. | N/A |
| Preventative Measures | Regularly inspect wiring and connectors for damage or corrosion. Avoid slamming doors to minimize stress on wiring. | N/A |
| Troubleshooting Tips | - Start with the simplest and most common causes first. - Use a systematic approach to narrow down the problem. - Consult a wiring diagram. - Don't assume the BCM is faulty unless all other possibilities have been ruled out. | N/A |
| Software Updates | In some cases, a BCM software update may resolve communication issues related to the power mirror system. | N/A |
| Specific Vehicle Models | The B1779 code can occur in various vehicle makes and models. The diagnostic procedure is generally similar, but wiring diagrams will vary. | N/A |
| Duration of Repair | Ranges from a few hours to several days, depending on the complexity of the problem and the availability of parts. | N/A |
| Safety Precautions | - Disconnect the negative battery terminal before working on electrical components. - Use appropriate tools and safety gear. - Consult a qualified technician if you are not comfortable performing electrical repairs. | N/A |
| Intermittent Issues | Intermittent issues can be difficult to diagnose. Check for loose connections or wiring that may be affected by temperature or vibration. | N/A |
| Warranty Coverage | If the vehicle is under warranty, the repair may be covered. | N/A |
| DIY vs. Professional | Simple repairs like replacing a fuse or connector can be done DIY, but more complex diagnostics and repairs should be left to a professional. | N/A |
| Testing with a Load | If possible, test the circuit with a load (e.g., the mirror motor) connected to ensure the circuit can carry current. | N/A |
Detailed Explanations
Definition of B1779: The B1779 diagnostic trouble code (DTC) is a manufacturer-specific code that indicates an open circuit in the wiring or components controlling the downward movement of a vehicle's side mirror. An open circuit means that the electrical path is broken, preventing current from flowing.
Affected System: The B1779 code specifically affects the power mirror system, particularly the circuit responsible for adjusting the mirror downward. This circuit includes the mirror switch, wiring, connectors, and the mirror motor itself.
Common Symptoms: The most obvious symptom of a B1779 code is the inability of the affected side mirror to move downward when the control is activated. Other mirror functions, such as upward, left, and right movement, might still function normally.
Possible Causes: Several factors can trigger a B1779 code:
- Open circuit in the wiring harness: A break in the wires connecting the mirror switch, mirror motor, and BCM is a common cause. This can be due to damage, corrosion, or wear and tear.
- Faulty mirror switch: The mirror switch itself may be defective, failing to properly complete the circuit when the "down" position is selected.
- Defective mirror motor: The mirror motor responsible for downward movement could be faulty, preventing the mirror from adjusting.
- Corroded or loose connectors: Corrosion or loose connections in the wiring harness can disrupt the electrical flow, leading to an open circuit.
- Faulty Body Control Module (BCM): While less common, a faulty BCM can incorrectly report or even cause an open circuit in the mirror control system.
- Blown fuse: Although less likely, a blown fuse in the power mirror circuit can also cause a B1779 code.
Diagnostic Tools: To diagnose a B1779 code effectively, you'll need the following tools:
- Multimeter: A multimeter is essential for testing voltage, continuity, and resistance in the electrical circuit.
- Wiring diagram: A vehicle-specific wiring diagram is crucial for identifying the correct wires and components to test.
- Scan tool: A scan tool can read and clear DTCs and may also provide access to BCM data for further diagnostics.
Diagnostic Steps: A systematic approach is essential for diagnosing a B1779 code:
- Visually inspect wiring and connectors: Carefully examine the wiring harness and connectors associated with the power mirror system for any signs of damage, corrosion, or loose connections.
- Test the mirror switch: Use a multimeter to check for continuity when the mirror switch is in the "down" position. Refer to the wiring diagram for the specific pin locations to test.
- Check the mirror motor: Directly apply voltage to the mirror motor to see if it moves. Refer to the wiring diagram for the correct polarity.
- Test the wiring harness: Use a multimeter to test the continuity of the wires in the wiring harness between the mirror switch, mirror motor, and BCM.
- Check the BCM: As a last resort, if all other components test good, the BCM may be faulty. However, this should be confirmed by a qualified technician.
Wiring Inspection Points: When inspecting the wiring, pay close attention to these points:
- Connector at the mirror assembly
- Connector at the mirror switch
- Wiring harness between the switch and the mirror
- Ground connections
Mirror Switch Testing: Use a multimeter set to the continuity setting. Place one probe on the common pin and the other probe on the pin that corresponds to the "down" position. When the switch is activated, the multimeter should show continuity.
Mirror Motor Testing: Disconnect the mirror motor connector. Using jumper wires, connect the motor directly to a 12V power source, observing the correct polarity as indicated in the wiring diagram. If the motor doesn't move, it's likely faulty.
BCM Involvement: The BCM controls various vehicle functions, including the power mirror system. A faulty BCM can incorrectly report or cause open circuits in the mirror control system. It's important to rule out other possibilities before suspecting the BCM.
Fuse Location: Consult the vehicle's owner's manual for the location of the fuse(s) related to the power mirror system. Check the fuse to ensure it's not blown.
Repair Strategies: Potential repair strategies for a B1779 code include:
- Repair or replace damaged wiring
- Replace faulty connectors
- Replace the mirror switch
- Replace the mirror motor
- Replace the BCM (if diagnosed as faulty)
Related DTCs: Other DTCs related to the power mirror system include:
- B1778 (Mirror Driver Up Circuit Open)
- B1780 (Mirror Driver Left Circuit Open)
- B1781 (Mirror Driver Right Circuit Open)
Impact on Safety: The inability to adjust the side mirror downward can reduce visibility and maneuverability, potentially compromising driving safety.
Estimated Repair Costs: Repair costs can vary widely depending on the cause of the B1779 code. Simple repairs, such as wiring repair, may be relatively inexpensive, while BCM replacement can be a significant expense.
Difficulty Level: Diagnosing and repairing a B1779 code can range from moderate to high in difficulty. It requires electrical troubleshooting skills and access to vehicle-specific wiring diagrams.
Tools Required: The following tools are typically required for diagnosing and repairing a B1779 code:
- Multimeter
- Wire strippers
- Wire connectors
- Socket set
- Screwdrivers
- Wiring diagram
Component Locations:
- Mirror Switch: Typically located on the door panel.
- Mirror Motor: Inside the mirror housing.
- BCM: Usually located under the dashboard.
Voltage Range: Power mirror systems typically operate on a 12V DC electrical system.
Ground Point: Ensure the ground point for the power mirror system is clean and securely connected. A poor ground connection can cause various electrical problems.
Connector Types: Multi-pin connectors are commonly used for mirror wiring. Inspect these connectors for corrosion or damage.
Wiring Color Codes: Refer to the vehicle-specific wiring diagram for accurate wiring color codes.
Mirror Types: Various types of mirrors exist, including manual, electric, heated, auto-dimming, and power-folding mirrors. The B1779 code specifically applies to electric power mirrors.
OEM vs. Aftermarket: OEM (Original Equipment Manufacturer) parts are generally recommended for critical components like the BCM. However, aftermarket mirror motors and switches may be acceptable.
Preventative Measures: Regularly inspect wiring and connectors for damage or corrosion. Avoid slamming doors to minimize stress on the wiring.
Troubleshooting Tips:
- Start with the simplest and most common causes first.
- Use a systematic approach to narrow down the problem.
- Consult a wiring diagram.
- Don't assume the BCM is faulty unless all other possibilities have been ruled out.
Software Updates: In some cases, a BCM software update may resolve communication issues related to the power mirror system.
Specific Vehicle Models: The B1779 code can occur in various vehicle makes and models. The diagnostic procedure is generally similar, but wiring diagrams will vary.
Duration of Repair: The repair duration can range from a few hours to several days, depending on the complexity of the problem and the availability of parts.
Safety Precautions:
- Disconnect the negative battery terminal before working on electrical components.
- Use appropriate tools and safety gear.
- Consult a qualified technician if you are not comfortable performing electrical repairs.
Intermittent Issues: Intermittent issues can be difficult to diagnose. Check for loose connections or wiring that may be affected by temperature or vibration.
Warranty Coverage: If the vehicle is under warranty, the repair may be covered.
DIY vs. Professional: Simple repairs like replacing a fuse or connector can be done DIY, but more complex diagnostics and repairs should be left to a professional.
Testing with a Load: If possible, test the circuit with a load (e.g., the mirror motor) connected to ensure the circuit can carry current.
Frequently Asked Questions
What does the B1779 code mean? The B1779 code indicates an open circuit in the wiring controlling the downward movement of your car's side mirror. This means the electrical path is broken, preventing the mirror from adjusting downwards.
What are the symptoms of a B1779 code? The main symptom is the inability to move the side mirror downwards using the power mirror control. Other mirror functions may still work normally.
What could cause the B1779 code? Possible causes include a broken wire, a faulty mirror switch, a defective mirror motor, or a problem with the BCM. Corroded connectors can also cause this issue.
How do I fix a B1779 code? Fixing the code involves diagnosing the open circuit and repairing or replacing the faulty component, such as the wiring, switch, or motor. Consulting a professional is recommended for complex issues.
Can I drive with a B1779 code? While you can drive, it's not recommended as it impacts your visibility, making driving less safe. It's best to address the issue as soon as possible.
Conclusion
The B1779 code indicates a problem with the electrical circuit that controls the downward movement of your vehicle's side mirror. By systematically diagnosing the potential causes, such as wiring issues, a faulty switch, or a defective motor, you can effectively troubleshoot and resolve the problem, restoring full functionality to your power mirror system. It's crucial to prioritize safety and seek professional assistance when dealing with complex electrical repairs.