B1735 Mirror Driver Vertical Switch Circuit Short To Battery

This article delves into the diagnostic and troubleshooting process for a B1735 diagnostic trouble code (DTC), specifically related to a "Mirror Driver Vertical Switch Circuit Short To Battery." This code indicates an electrical fault within the system controlling the vertical movement of the side mirrors, where an unintended electrical path is established, causing a short circuit to the vehicle's battery voltage. Understanding the underlying causes and implementing proper diagnostic procedures are crucial for efficient and effective repair.

B1735 Diagnostic Trouble Code (DTC) Explained

Detailed Explanations

DTC Definition: Mirror Driver Vertical Switch Circuit Short To Battery

This DTC, B1735, signifies that the vehicle's onboard computer (typically the body control module or a dedicated door control module) has detected an abnormal voltage level in the circuit responsible for controlling the vertical movement of the side mirror. Specifically, the voltage is excessively high, indicating an unintended connection to the vehicle's battery voltage. This "short to battery" condition prevents the circuit from functioning correctly and can potentially damage components.

Symptoms

• Side mirror vertical adjustment malfunction: This is the most obvious symptom. The mirror may not move up or down at all, it might move erratically, or it might move in the wrong direction.

• Fuse blowing related to the mirror or door control module circuit: A short to battery often draws excessive current, which can cause the fuse protecting the circuit to blow. Repeatedly blown fuses are a strong indicator of a short circuit.

• Battery drain: A constant short to battery can draw power even when the vehicle is off, leading to a drained battery.

• Possible other electrical malfunctions related to the door control module: The door control module typically controls other functions, such as power windows and door locks. A fault in the mirror circuit could potentially affect these other functions.

• Diagnostic Trouble Code (DTC) B1735 stored in the vehicle's computer: This code is the primary indicator of the problem and will be stored in the vehicle's computer's memory. It can be retrieved using a diagnostic scan tool.

Possible Causes

• Short circuit in the mirror driver vertical switch circuit: This is the most common cause. The insulation on a wire in the circuit may be damaged, allowing the wire to come into contact with a grounded metal surface or another wire carrying battery voltage. This can be caused by chafing, pinching, or general wear and tear.

• Faulty mirror driver vertical switch: The switch itself could be internally shorted, causing the circuit to be constantly connected to battery voltage.

• Faulty door control module: Although less common, the door control module itself could be malfunctioning internally, causing the short circuit.

• Wiring harness damage: The wiring harness that contains the mirror control wires can be damaged due to chafing, corrosion, or being pinched during repairs.

• Loose or corroded connectors: Loose or corroded connectors can create resistance and voltage drops, which can sometimes trigger false DTCs or exacerbate existing problems.

• Internal short within the side mirror assembly: The motor or wiring within the mirror assembly itself could be shorted to battery voltage.

Diagnostic Steps

• Perform a visual inspection of the wiring and connectors: Carefully inspect the wiring and connectors associated with the side mirror and door control module. Look for signs of damage, such as chafing, cuts, corrosion, or loose connections. Pay close attention to areas where the wiring harness passes through the door jamb, as this is a common location for damage.

• Check for blown fuses: Consult the vehicle's owner's manual or a wiring diagram to identify the fuse(s) that protect the mirror circuit. Check the fuse(s) to see if they are blown. If a fuse is blown, replace it with a fuse of the correct amperage. If the fuse blows again immediately, it is a strong indication of a short circuit.

• Use a multimeter to test the voltage and continuity: Use a multimeter to test the voltage and continuity of the mirror driver vertical switch circuit. Refer to the vehicle's wiring diagram to identify the correct wires to test. Check for voltage on the circuit with the switch in the "off" position; there should be no voltage. Check for continuity between the circuit and ground; there should be no continuity. A voltage reading with the switch off or continuity to ground indicates a short circuit.

• Disconnect the mirror assembly and re-test the circuit: Disconnecting the mirror assembly will isolate the mirror itself as the source of the problem. If the short disappears when the mirror is disconnected, the fault lies within the mirror assembly.

• Test the mirror driver vertical switch: Use a multimeter to test the mirror driver vertical switch for proper operation. Check for continuity between the switch terminals in the different switch positions. Refer to the vehicle's wiring diagram to understand the switch's operation.

• Inspect the door control module: Visually inspect the door control module for any signs of damage, such as corrosion or burnt components.

• Consult the vehicle's wiring diagram: A wiring diagram is essential for tracing the circuit and identifying potential short locations. It will show the routing of the wires, the location of connectors, and the components that are connected to the circuit.

• Use a scan tool to monitor the data stream: A scan tool can be used to monitor the data stream from the door control module. This can provide information about the status of the mirror circuit and the commands being sent to the mirror motor.

Frequently Asked Questions

What does "Short To Battery" mean?

It means that a wire or component in the circuit is unintentionally connected to the positive voltage of the vehicle's battery.

Can a B1735 code drain my car battery?

Yes, a short to battery can cause a constant drain on the battery, even when the vehicle is turned off.

Is it safe to drive with a B1735 code?

It is generally safe to drive, but the mirror adjustment will likely be malfunctioning, and there's a risk of further electrical issues or a fire if the short is severe.

Can I fix a B1735 code myself?

If you have experience with automotive electrical systems and are comfortable using a multimeter and wiring diagrams, you may be able to diagnose and repair the problem yourself. However, if you are not confident in your abilities, it is best to take the vehicle to a qualified mechanic.

How much does it cost to fix a B1735 code?

The cost to fix a B1735 code can vary depending on the cause of the problem. A simple repair, such as replacing a blown fuse or repairing a damaged wire, may cost only a few dollars. However, a more complex repair, such as replacing the door control module or the mirror assembly, could cost several hundred dollars.

Conclusion

The B1735 DTC indicates a serious electrical fault that requires careful diagnosis. By following the diagnostic steps outlined above, you can systematically identify the cause of the short circuit and implement the necessary repairs. Addressing this issue promptly is crucial to prevent further damage to the vehicle's electrical system and ensure the proper functioning of the side mirrors.