The B1702 diagnostic trouble code (DTC) indicates a fault within the mirror switch circuit, specifically that the "L" (likely Left) input is shorted to ground. This means there's an unintended electrical connection between the wire carrying the signal from the left mirror control and the vehicle's chassis ground. This short circuit can prevent the mirror from functioning correctly and potentially cause other electrical issues.
This code is typically associated with the power mirror system, which allows the driver to adjust the side mirrors electronically. When this system malfunctions, it can significantly reduce visibility and compromise driving safety. Understanding the causes and troubleshooting steps for this code is crucial for proper vehicle maintenance and repair.
| Topic | Description | Potential Impact |
|---|---|---|
| Code Definition | B1702 - Mirror Switch L Input Shorted to Ground. Indicates an unwanted electrical connection between the left mirror control signal wire and the vehicle's chassis ground. | Malfunctioning left side mirror adjustment, potential for blown fuses, and possibly damage to the mirror switch or related control modules. |
| Affected Components | Mirror switch assembly, wiring harness connecting the mirror switch to the mirror motor and body control module (BCM), left mirror motor, and potentially the BCM itself. | Non-functional left side mirror adjustment, difficulty seeing blind spots, increased risk of accidents, and potential for further electrical system damage. |
| Possible Causes | Damaged wiring (frayed, pinched, or cut), faulty mirror switch, corroded connectors, short circuit within the mirror motor itself, or a malfunctioning BCM. | Intermittent mirror operation, complete failure of mirror adjustment, blown fuses, and potential fire hazard in severe cases. |
| Symptoms | Left side mirror not adjusting, mirror moving erratically or not at all, blown fuses related to the mirror circuit, possible battery drain, and potentially other electrical malfunctions. | Reduced visibility, difficulty parking, increased risk of accidents, and potential for further electrical system damage. |
| Diagnostic Steps | Visual inspection of wiring and connectors, testing the mirror switch for continuity and proper operation, checking for shorts to ground in the wiring harness, and potentially testing the BCM. | Time-consuming troubleshooting process, potential need for specialized tools and equipment, and the possibility of misdiagnosis leading to unnecessary repairs. |
| Troubleshooting Tools | Multimeter, wiring diagrams, scan tool (for reading and clearing codes), and potentially a circuit tester. | Expense of purchasing or renting specialized tools, potential for damage to electrical components if used incorrectly, and the need for technical knowledge to operate. |
| Common Repair Solutions | Replacing damaged wiring, replacing the faulty mirror switch, cleaning or replacing corroded connectors, and potentially replacing the mirror motor or BCM (in rare cases). | Cost of replacement parts, labor costs if hiring a mechanic, and the potential for recurrence if the underlying cause is not properly addressed. |
| Related DTCs | Other mirror-related DTCs (e.g., B1701, B1703, B1704) and potentially codes related to other electrical components sharing the same circuit or ground. | Confusing diagnosis, difficulty identifying the root cause of the problem, and potential for misdiagnosis leading to unnecessary repairs. |
| Safety Precautions | Disconnect the battery before working on electrical components to prevent accidental shocks or further damage. Consult a qualified technician if you are not comfortable working with electrical systems. | Risk of electrical shock, damage to vehicle electrical system, and potential for personal injury. |
Detailed Explanations
Code Definition: The B1702 code is a specific diagnostic code indicating a fault in the mirror switch circuit. The "L" usually designates the Left side mirror control signal. A "short to ground" means the wire carrying the signal from the mirror switch to the left mirror motor or body control module (BCM) is making unintended contact with the vehicle's metal chassis. This unintended connection allows electricity to flow directly to ground, bypassing the intended circuit and preventing the mirror from functioning correctly.
Affected Components: The most common components affected are the mirror switch itself, the wiring harness connecting the switch to the mirror motor and BCM, the left mirror motor, and less frequently, the BCM. The mirror switch is responsible for sending signals to the mirror motor to adjust its position. The wiring harness provides the electrical pathway for these signals. The mirror motor receives the signals and moves the mirror accordingly. The BCM acts as a central control unit for various vehicle functions, including the mirror system in some vehicles.
Possible Causes: Several factors can lead to a B1702 code. Damaged wiring is a frequent culprit. This includes frayed, pinched, or cut wires that expose the conductive core and allow it to contact the vehicle's chassis. A faulty mirror switch can also cause a short to ground internally. Corroded connectors can create resistance and lead to shorts. A short circuit within the mirror motor itself is less common but possible. Finally, although rare, a malfunctioning BCM can misinterpret signals or cause a short within its internal circuitry.
Symptoms: The primary symptom is the left side mirror not adjusting when the mirror switch is operated. The mirror might move erratically, move in only one direction, or not move at all. Blown fuses related to the mirror circuit are another common symptom, as the short to ground draws excessive current. In some cases, a battery drain might occur if the short is persistent. Other electrical malfunctions could arise if the short interferes with other circuits.
Diagnostic Steps: The first step is a visual inspection of the wiring and connectors associated with the mirror switch and left side mirror. Look for any signs of damage, corrosion, or loose connections. Next, test the mirror switch for continuity and proper operation using a multimeter. Check for shorts to ground in the wiring harness using a multimeter set to measure resistance. Finally, if the other tests don't reveal the problem, you may need to test the BCM, which often requires specialized equipment and expertise.
Troubleshooting Tools: A multimeter is essential for testing continuity, voltage, and resistance in the circuit. Wiring diagrams are crucial for understanding the circuit layout and identifying the correct wires to test. A scan tool can be used to read and clear DTCs. A circuit tester can quickly identify whether a wire is carrying power or ground.
Common Repair Solutions: The most common repair is replacing damaged wiring or repairing any breaks in the wire. Replacing the faulty mirror switch is often necessary if the switch itself is the source of the short. Cleaning or replacing corroded connectors can restore proper electrical contact. In rare cases, replacing the mirror motor or BCM might be required, but these are more expensive and complex repairs.
Related DTCs: Other mirror-related DTCs, such as B1701 (Mirror Switch R Input Shorted to Ground), B1703 (Mirror Switch Up Input Shorted to Ground), and B1704 (Mirror Switch Down Input Shorted to Ground), might be present. Additionally, codes related to other electrical components sharing the same circuit or ground could also appear. These related codes can help narrow down the source of the problem.
Safety Precautions: Always disconnect the battery before working on any electrical components to prevent accidental shocks or further damage to the vehicle's electrical system. If you are not comfortable working with electrical systems, consult a qualified technician for assistance. Incorrectly diagnosing or repairing electrical problems can be dangerous and could potentially cause further damage to the vehicle.
Frequently Asked Questions
What does B1702 mean? It means the "L" (usually Left) input of the mirror switch is shorted to ground, indicating an unintended electrical connection to the vehicle's chassis. This prevents the left mirror from adjusting correctly.
How do I fix a B1702 code? Inspect the wiring and connectors for damage, test the mirror switch, and check for shorts to ground in the wiring harness. Repair or replace any faulty components.
Can a bad mirror switch cause a B1702 code? Yes, a faulty mirror switch can internally create a short to ground, triggering the B1702 code. Testing the switch is a crucial diagnostic step.
Is B1702 a serious problem? While not immediately critical, it affects visibility and safety. Address it promptly to ensure proper mirror function and prevent further electrical issues.
Will a B1702 code cause my battery to drain? Potentially, a persistent short to ground can cause a parasitic battery drain, especially if the short is constantly active.
Conclusion
The B1702 code signifies a short to ground in the left mirror switch input, typically leading to a malfunctioning left side mirror. Thorough diagnosis, including visual inspection, component testing, and wiring checks, is essential for effective repair and ensuring optimal vehicle safety.