The B1739 diagnostic trouble code (DTC) indicates a problem within the mirror control system of a vehicle, specifically a short to battery voltage in the horizontal switch circuit of the mirror driver. This means the circuit designed to move the mirror horizontally (left and right) is receiving unintended power directly from the vehicle's battery, leading to potential malfunctions and electrical issues. Addressing this promptly is crucial to prevent further damage to the mirror system and the vehicle's electrical system.
Table of Information: B1739 Mirror Driver Horizontal Switch Circuit Short To Battery
| Topic | Description | Possible Causes |
|---|---|---|
| Definition of B1739 | Diagnostic Trouble Code (DTC) indicating a short to battery voltage in the horizontal switch circuit of the mirror driver. This means the circuit is receiving power directly from the battery when it should not be, causing potential malfunctions. | Faulty mirror switch, damaged wiring harness, shorted mirror motor, internal short within the mirror driver module, corrosion in connectors or wiring, rubbed wires, faulty ground connections, or a damaged fuse box/wiring. |
| Symptoms of B1739 | Mirror moves erratically or not at all horizontally, mirror moves constantly in one direction horizontally, blown fuses related to the mirror system, battery drain, inoperative power mirrors, other electrical issues in the vehicle, unusual noises from the mirror assembly. | |
| Affected Components | Mirror switch, mirror motor, wiring harness connecting the mirror components, mirror driver module (if equipped), related fuses and relays, battery, ground connections. | |
| Diagnostic Steps | Visual inspection of wiring and connectors, testing the mirror switch, checking for voltage at the mirror motor, testing the mirror motor itself, checking for continuity in the wiring, checking fuses and relays, inspecting the mirror driver module (if equipped). | |
| Tools Required for Diagnosis | Multimeter, wiring diagram, test light, basic hand tools (screwdrivers, pliers, wire strippers), scan tool (optional, for reading DTCs and live data). | |
| Potential Repair Solutions | Replacing the faulty mirror switch, repairing or replacing the damaged wiring harness, replacing the shorted mirror motor, replacing the faulty mirror driver module (if equipped), cleaning corroded connectors, repairing faulty ground connections, replacing blown fuses. | |
| Severity of the Problem | Moderate to High. A short to battery can lead to electrical damage, battery drain, and inoperative safety features. Prompt diagnosis and repair are recommended. | |
| Related Diagnostic Codes | Other mirror-related DTCs (e.g., for vertical movement, motor circuit issues), DTCs related to battery voltage or electrical system malfunctions. | |
| Mirror Driver Module Function | The mirror driver module (if equipped) controls the power mirrors based on inputs from the mirror switch. It regulates voltage and current to the mirror motors to achieve the desired mirror position. | |
| Horizontal Switch Circuit | The specific wiring and components dedicated to controlling the left/right movement of the mirror. This circuit includes the switch contacts, wiring, and possibly transistors or other electronic components within the mirror driver module. | |
| Symptoms of a Short to Battery | Higher-than-normal voltage readings in the affected circuit, blown fuses, potential damage to components due to excessive current flow, and unintended activation of the mirror motor. | |
| Importance of Wiring Diagrams | Essential for tracing the circuit path, identifying components, and determining the correct voltage and resistance readings. A wiring diagram allows for accurate testing and troubleshooting. |
Detailed Explanations
Definition of B1739: This code signifies that the control circuit responsible for the horizontal movement of the power mirrors is receiving direct battery voltage when it shouldn't. This unintended voltage can cause the mirror to move on its own, not move at all, or blow fuses. Essentially, a path to the battery has been created where one shouldn't exist within that specific circuit.
Symptoms of B1739: The most common symptom is erratic or non-functional horizontal mirror movement. Other signs include continuously moving mirrors, blown fuses, battery drain, and other electrical problems. You might also hear unusual noises coming from the mirror motor as it attempts to adjust.
Affected Components: The fault could reside in the mirror switch itself, the wiring harness connecting the switch to the mirror motor, the mirror motor, the mirror driver module (if present), or even the fuses and relays associated with the mirror system. Ground connections are also critical and can cause issues if corroded or loose.
Diagnostic Steps: Begin with a visual inspection of the wiring and connectors for any signs of damage or corrosion. Next, test the mirror switch for proper function using a multimeter. Check for voltage at the mirror motor when the switch is activated. If the wiring and switch seem fine, the motor itself or the mirror driver module might be the culprit. Use a wiring diagram to trace the circuit and test for continuity.
Tools Required for Diagnosis: You'll need a multimeter to measure voltage and resistance, a wiring diagram to understand the circuit layout, a test light to check for power, and basic hand tools like screwdrivers and pliers. A scan tool can be helpful for reading the DTC and accessing live data from the vehicle's computer.
Potential Repair Solutions: Depending on the diagnosis, you might need to replace the mirror switch, repair damaged wiring, replace the mirror motor, or replace the mirror driver module. Cleaning corroded connectors and repairing faulty ground connections can also resolve the issue. Always replace any blown fuses with the correct amperage rating.
Severity of the Problem: A short to battery is a moderate to high severity issue. It can lead to electrical damage, battery drain, and potentially affect other systems in the vehicle. It's important to address this issue promptly to prevent further complications.
Related Diagnostic Codes: You might encounter other mirror-related DTCs, such as those for vertical mirror movement or motor circuit issues. Also, look for codes related to battery voltage or general electrical system malfunctions.
Mirror Driver Module Function: The mirror driver module acts as an intermediary between the mirror switch and the mirror motors. It receives signals from the switch and then controls the voltage and current supplied to the motors, allowing for precise mirror adjustments. Some vehicles don't have a separate module and rely solely on the switch and wiring.
Horizontal Switch Circuit: This is the specific part of the electrical system dedicated to controlling the left/right movement of the mirror. It includes the switch contacts that activate the motor, the wiring that carries the electrical signal, and potentially electronic components within the mirror driver module that regulate the current flow.
Symptoms of a Short to Battery: A short to battery in this circuit will result in higher-than-normal voltage readings when measured with a multimeter. It can also cause fuses to blow repeatedly, and the mirror motor might activate unexpectedly. Over time, the excessive current flow can damage the motor or other components in the circuit.
Importance of Wiring Diagrams: A wiring diagram is absolutely essential for diagnosing electrical problems like a B1739 code. It provides a detailed map of the circuit, showing the location of components, the wire colors, and the connections between them. This allows you to trace the circuit path, identify potential problem areas, and verify voltage and resistance readings at various points.
Frequently Asked Questions
What does the B1739 code mean? It indicates a short to battery in the horizontal switch circuit of the mirror driver, meaning the circuit is receiving unintended power directly from the battery.
Can I fix a B1739 code myself? If you have experience with automotive electrical systems and can follow a wiring diagram, you might be able to diagnose and repair the problem yourself. However, it's recommended to consult a qualified technician if you're not comfortable working with electrical systems.
What are the symptoms of a B1739 code? Erratic or non-functional horizontal mirror movement, blown fuses, and battery drain are common symptoms.
What tools do I need to diagnose a B1739 code? A multimeter, wiring diagram, test light, and basic hand tools are essential for diagnosing this issue.
How serious is a B1739 code? It's a moderate to high severity issue that should be addressed promptly to prevent electrical damage and potential battery drain.
Conclusion
The B1739 DTC points to a short to battery in the horizontal switch circuit of the mirror driver. Thorough diagnosis using a wiring diagram and appropriate tools is crucial for identifying and resolving the root cause. Addressing this issue promptly will prevent further electrical damage and ensure the proper functioning of your vehicle's mirror system.