The B1703 diagnostic trouble code (DTC) indicates a fault within the vehicle's electrical system, specifically related to the left-side (driver's side in many markets) mirror switch. This code signifies that the signal from the "down" input of the mirror switch is constantly registering as "high," meaning the system believes the driver is continuously requesting the mirror to move downward. This can prevent proper mirror adjustment and potentially cause other electrical issues. Addressing this code promptly is important to ensure optimal vehicle functionality and safety.

Category Description Possible Causes
Code Definition B1703 - Mirror Switch L Down Input Stuck High A malfunction in the electrical circuit of the driver's side mirror control switch, specifically the "down" input.
Symptoms Mirror will not adjust upward, Mirror moves downward continuously, Intermittent mirror adjustment, Mirror adjustment not working at all, Error code present Continuous downward mirror movement, Inability to adjust the mirror upward, Erratic mirror behavior, Complete mirror control failure.
Possible Causes Faulty mirror switch, Short circuit in the wiring harness, Open circuit in the wiring harness, Damaged connector, Corroded terminals, Faulty body control module (BCM), Software issue Defective switch mechanism, Damaged or frayed wires, Broken wires, Loose connection, Corrosion buildup, BCM malfunction, Software glitch.
Diagnostic Steps Visual inspection of wiring and connectors, Check for voltage at the switch, Test the switch for continuity, Check for shorts to ground or voltage, Check for open circuits, Test the BCM, Check for software updates Inspect wires for damage, Use a multimeter to measure voltage, Use a multimeter to test continuity, Use a multimeter to check for shorts, Use a multimeter to check for opens, Use a scan tool to test the BCM, Check the vehicle's computer for software updates.
Possible Solutions Replace the mirror switch, Repair or replace the wiring harness, Clean or replace connectors, Replace the BCM, Reprogram the BCM Install a new switch, Repair damaged wires, Replace damaged wires, Clean corroded terminals, Replace corroded terminals, Replace the BCM, Update the BCM software.
Severity Moderate Can affect driving safety by limiting visibility. May also drain battery if the motor is constantly running.
Related Codes B1701 (Mirror Switch L Up Input Stuck High), B1702 (Mirror Switch L Right Input Stuck High), B1704 (Mirror Switch L Left Input Stuck High), B1705 (Mirror Switch R Up Input Stuck High), B1706 (Mirror Switch R Down Input Stuck High), B1707 (Mirror Switch R Right Input Stuck High), B1708 (Mirror Switch R Left Input Stuck High) These codes relate to other mirror switch inputs or the opposite side mirror.
Tools Required Multimeter, Scan tool, Wiring diagram, Basic hand tools (screwdrivers, pliers, etc.) Used to test electrical circuits, read diagnostic codes, understand wiring configurations, and perform repairs.
Estimated Repair Cost $50 - $500+ Varies depending on the cause and whether you DIY or hire a mechanic. Switch replacement is relatively inexpensive; BCM replacement can be costly.
Skill Level Required Beginner to Advanced Simple tasks like switch replacement can be done by beginners. More complex electrical diagnosis and BCM replacement require advanced skills.

Detailed Explanations

Code Definition: B1703 - Mirror Switch L Down Input Stuck High

This code indicates that the vehicle's computer has detected a persistent "high" signal from the "down" input circuit of the left (driver's side) mirror switch. The Body Control Module (BCM), or a similar control unit, monitors the signals from the mirror switch. A "high" signal typically signifies that the switch is activated, requesting the mirror to move downwards. When this signal is constantly present, even when the switch is not physically pressed, the B1703 code is triggered.

Symptoms

  • Mirror will not adjust upward: Because the system thinks the "down" command is always active, it may prevent any upward movement.
  • Mirror moves downward continuously: The mirror may attempt to adjust downwards even without driver input.
  • Intermittent mirror adjustment: The mirror may function erratically, moving in unpredictable directions or not responding consistently to switch inputs.
  • Mirror adjustment not working at all: In some cases, the entire mirror adjustment function may cease to operate.
  • Error code present: The B1703 code is stored in the vehicle's computer and can be retrieved using a scan tool.

Possible Causes

  • Faulty mirror switch: The internal contacts of the switch may be damaged or stuck in the "down" position, causing a constant signal.
  • Short circuit in the wiring harness: A short circuit to a voltage source in the wiring connected to the switch can create a continuous "high" signal.
  • Open circuit in the wiring harness: While seemingly counterintuitive, an open circuit combined with a pull-up resistor in the circuit design can cause a "high" signal.
  • Damaged connector: Corrosion, bent pins, or loose connections within the connector can disrupt the signal and cause a false "high" reading.
  • Corroded terminals: Corrosion on the switch terminals or wiring terminals can create a resistance that interferes with the signal.
  • Faulty body control module (BCM): In rare cases, the BCM itself may be malfunctioning and misinterpreting the signal from the switch.
  • Software issue: Though less common, a software glitch within the BCM can potentially lead to incorrect signal interpretation.

Diagnostic Steps

  • Visual inspection of wiring and connectors: Carefully inspect the wiring harness and connectors associated with the mirror switch for any signs of damage, such as frayed wires, exposed conductors, or corrosion.
  • Check for voltage at the switch: Use a multimeter to measure the voltage at the switch terminals. Ensure that the voltage matches the expected voltage according to the vehicle's wiring diagram.
  • Test the switch for continuity: Use a multimeter to test the continuity of the switch in both the "off" and "on" positions. The switch should only show continuity when the "down" position is selected.
  • Check for shorts to ground or voltage: Use a multimeter to check for any shorts to ground or voltage in the wiring harness. A short to ground can cause a constant "high" signal.
  • Check for open circuits: Use a multimeter to check for any open circuits in the wiring harness.
  • Test the BCM: Use a scan tool to test the functionality of the BCM and check for any other related error codes.
  • Check for software updates: Ensure that the BCM has the latest software updates installed.

Possible Solutions

  • Replace the mirror switch: If the switch is found to be faulty, replacing it is the most common solution.
  • Repair or replace the wiring harness: If the wiring harness is damaged, repair or replace it to restore proper signal transmission.
  • Clean or replace connectors: Clean any corroded connectors or replace them if they are severely damaged.
  • Replace the BCM: If the BCM is found to be faulty, replacing it is necessary.
  • Reprogram the BCM: If a software glitch is suspected, reprogramming the BCM may resolve the issue.

Severity

The severity of the B1703 code is considered moderate. While it may not immediately disable the vehicle, it can significantly impact driving safety by limiting the driver's ability to properly adjust the side mirror. This reduced visibility can increase the risk of accidents. Furthermore, if the mirror motor is constantly running in an attempt to move the mirror downwards, it could potentially drain the vehicle's battery.

Related Codes

  • B1701 (Mirror Switch L Up Input Stuck High): Indicates a similar issue with the "up" input of the left mirror switch.
  • B1702 (Mirror Switch L Right Input Stuck High): Indicates a similar issue with the "right" input of the left mirror switch.
  • B1704 (Mirror Switch L Left Input Stuck High): Indicates a similar issue with the "left" input of the left mirror switch.
  • B1705 (Mirror Switch R Up Input Stuck High): Indicates a similar issue with the "up" input of the right mirror switch.
  • B1706 (Mirror Switch R Down Input Stuck High): Indicates a similar issue with the "down" input of the right mirror switch.
  • B1707 (Mirror Switch R Right Input Stuck High): Indicates a similar issue with the "right" input of the right mirror switch.
  • B1708 (Mirror Switch R Left Input Stuck High): Indicates a similar issue with the "left" input of the right mirror switch.

These related codes can help pinpoint the exact location and nature of the mirror switch malfunction.

Tools Required

  • Multimeter: Essential for testing voltage, continuity, and resistance in electrical circuits.
  • Scan tool: Used to read diagnostic codes, clear codes, and potentially test the functionality of the BCM.
  • Wiring diagram: Provides a detailed map of the electrical circuits, including the wiring connections for the mirror switch.
  • Basic hand tools (screwdrivers, pliers, etc.): Necessary for removing panels, accessing connectors, and performing repairs.

Estimated Repair Cost

The cost of repairing a B1703 code can vary significantly depending on the root cause of the problem. A simple switch replacement can cost anywhere from $50 to $200, including parts and labor. However, if the issue is with the wiring harness or the BCM, the repair cost can easily exceed $500 or more. DIY repairs can significantly reduce costs if you have the necessary skills and tools.

Skill Level Required

Diagnosing and repairing a B1703 code can range from beginner to advanced, depending on the complexity of the issue. Replacing the mirror switch is a relatively straightforward task that can be performed by someone with basic mechanical skills. However, troubleshooting electrical problems in the wiring harness or diagnosing a faulty BCM requires more advanced knowledge and experience.

Frequently Asked Questions

What does the B1703 code mean? It means the vehicle's computer detects a constant "high" signal from the left mirror switch's "down" input, indicating a potential fault.

Can I still drive my car with a B1703 code? Yes, but your ability to adjust the driver-side mirror will be limited, potentially impacting safety.

Is the B1703 code a serious problem? It's moderately serious, as it affects visibility and could potentially drain the battery.

How do I fix the B1703 code? Possible solutions include replacing the mirror switch, repairing the wiring, or replacing the BCM.

Can I fix the B1703 code myself? If you're comfortable with basic electrical troubleshooting, you might be able to replace the switch yourself.

Conclusion

The B1703 code signifies a problem with the left mirror switch's "down" input, indicating it's stuck in a "high" state. Diagnosing and addressing this issue promptly is crucial for ensuring optimal visibility and safe driving conditions. A systematic approach, starting with a visual inspection and progressing to more advanced electrical testing, will help pinpoint the root cause and facilitate effective repair.