B1707 - Mirror Switch R Input Shorted to Ground

Introduction:

The diagnostic trouble code (DTC) B1707, "Mirror Switch R Input Shorted to Ground," indicates an electrical fault within the mirror control system of a vehicle. Specifically, it points to a short circuit to ground on the input signal from the mirror switch related to the right-side mirror adjustment. Addressing this code promptly is crucial for restoring proper mirror functionality and ensuring safe driving.

Comprehensive Table:

Detailed Explanations:

Code Definition: The B1707 code specifically identifies a problem with the electrical circuit that controls the right-side mirror adjustment. The vehicle's computer expects a certain voltage signal from the mirror switch when the driver attempts to adjust the mirror. If the computer detects that this signal wire is constantly connected to ground (i.e., a short circuit), it interprets this as a fault and sets the B1707 code. This short circuit prevents the control module from correctly interpreting the driver's instructions, resulting in the mirror not functioning properly.

Symptoms: The most obvious symptom is the inability to adjust the right-side mirror. Other potential symptoms include the mirror moving erratically or not responding to switch inputs at all. In some cases, other mirror functions, such as the left-side mirror or the mirror defrost, may also be affected due to shared circuitry or a power supply issue. A blown fuse in the mirror circuit is a strong indicator of a short circuit. Intermittent operation, where the mirror works sometimes but not others, can also point to a short that is making and breaking contact.

Possible Causes: Damaged Wiring: Wiring can become damaged due to age, exposure to the elements, or physical stress. This damage can lead to the insulation cracking or fraying, exposing the bare wire. If this exposed wire comes into contact with the vehicle's chassis or another ground point, it creates a short circuit. Rodent damage is also a common cause of damaged wiring in vehicles.

Possible Causes: Short Circuit: A short circuit is an unintended electrical connection between a component or wire and ground. In the context of the B1707 code, this means the wire carrying the signal from the mirror switch to the control module is directly connected to a ground point, such as the vehicle's frame or another grounded wire. This direct connection bypasses the intended circuit path and provides a low-resistance path for current to flow to ground.

Possible Causes: Faulty Mirror Switch: The mirror switch is responsible for sending signals to the control module to adjust the mirror. If the switch has an internal short circuit, it could be constantly grounding the input signal for the right-side mirror. This internal failure can occur due to wear and tear, contamination, or electrical damage. Testing the switch with a multimeter can help determine if it is functioning correctly.

Possible Causes: Corroded Connectors: Electrical connectors are susceptible to corrosion, especially in areas exposed to moisture and road salt. Corrosion can create a conductive path between the terminals in the connector, effectively creating a short circuit. Cleaning and inspecting the connectors is an important step in diagnosing the B1707 code. Dielectric grease can be applied to clean connectors to prevent further corrosion.

Possible Causes: Damaged Mirror Motor: While less common, a short circuit within the mirror motor itself can affect the mirror switch signal. If the motor has an internal fault, it can draw excessive current and potentially ground the circuit, leading to the B1707 code. Disconnecting the motor and retesting the circuit can help determine if the motor is the source of the problem.

Possible Causes: Faulty Control Module (Rare): In very rare instances, a problem with the body control module (BCM) or a dedicated mirror control module (if equipped) can cause the B1707 code. These modules are responsible for processing the signals from the mirror switch and controlling the mirror motor. If the module malfunctions, it may misinterpret the signals or incorrectly ground the circuit. This is usually diagnosed after all other potential causes have been ruled out.

Diagnostic Steps: Visual Inspection: A thorough visual inspection is the first and often most important step in diagnosing any electrical problem. Carefully examine the wiring harness leading to the mirror switch and the right-side mirror. Look for any signs of damage, such as frayed wires, cracked insulation, or corroded connectors. Pay close attention to areas where the wiring harness is routed near sharp edges or moving parts, as these are common locations for damage.

Diagnostic Steps: Voltage Testing: Use a multimeter set to the DC voltage setting to check the voltage at the mirror switch input wire. Consult a vehicle-specific wiring diagram to identify the correct wire. With the ignition on and the mirror switch in a neutral position, you should expect to see a voltage reading that is a significant portion of the vehicle's battery voltage (e.g., 10-12 volts). If the voltage reading is close to 0 volts, it indicates a short to ground.

Diagnostic Steps: Continuity Testing: Continuity testing should be performed with the circuit disconnected from the power source to avoid damaging the multimeter. Use a multimeter set to the continuity setting (often indicated by a diode symbol or audible beep). Connect one lead of the multimeter to the mirror switch input wire and the other lead to a known good ground point on the vehicle's chassis. If the multimeter shows continuity (a beep or a low resistance reading), it confirms a short circuit to ground.

Diagnostic Steps: Component Testing: The mirror switch can be tested for proper function using a multimeter. Consult a wiring diagram to identify the correct terminals for each switch position. The mirror motor can also be tested by applying a small voltage directly to the motor terminals to see if it operates. If the motor does not respond or draws excessive current, it may be faulty.

Diagnostic Steps: Wiring Diagram: A vehicle-specific wiring diagram is an essential tool for diagnosing the B1707 code. The wiring diagram shows the complete mirror circuit, including the location of the mirror switch, mirror motor, control module, and all associated wiring and connectors. This allows you to trace the circuit and identify potential short locations.

Diagnostic Steps: Control Module Check: This should be the final step in the diagnostic process, performed only after all other potential causes have been eliminated. Testing the control module typically requires specialized equipment and knowledge. In some cases, the module may need to be reprogrammed or replaced.

Frequently Asked Questions:

• What does the B1707 code mean? The B1707 code signifies that the signal wire for the right-side mirror adjustment is shorted to ground.

• Can I fix the B1707 code myself? Depending on your mechanical and electrical skills, you might be able to diagnose and repair the problem yourself, but proper tools and a wiring diagram are essential.

• How much will it cost to fix the B1707 code? The cost of repair can vary widely depending on the cause of the short and the labor rates in your area. A simple wiring repair might be inexpensive, while replacing a faulty switch or control module can be more costly.

• Can I still drive my car with the B1707 code? While you can technically drive the car, the right-side mirror will likely not function properly, which can be a safety hazard.

• How do I clear the B1707 code? After repairing the short circuit, you can clear the code using an OBD-II scanner.

Conclusion:

The B1707 code indicates a short circuit in the right-side mirror control circuit, leading to potential mirror malfunction. A thorough diagnostic process, including visual inspection, voltage testing, and component testing, is crucial for identifying and resolving the issue.