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DTC codes / B01xx · Airbags, seats, doors, lights and comfort systems / B0102

B0102Power Mirror Switch Circuit

B0102 indicates a fault in the power mirror switch circuit, which is the electrical path between the mirror control switch and the body control module (BCM) or dedicated mirror module. The computer has detected an abnormal voltage or current on the switch signal circuit, such as a short to ground, short to power, or open circuit, preventing it from reliably commanding the mirrors.

SystemBody
Code typeGeneric (all makes)
SeverityLow
Fix difficultyIntermediate
AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

  • One or both power mirrors fail to move in any direction
  • Mirror moves only in some directions or moves intermittently
  • Mirror switch feels loose or unresponsive when pressed
  • Often no symptoms besides the warning light, especially if the fault is intermittent
  • Memory mirror positions may not recall correctly if the switch signal is erratic
  • Mirror may move on its own or not stop when the switch is released

Common causes, most likely first

  1. Faulty power mirror switch (worn contacts or internal failure)
  2. Damaged or corroded wiring harness between the door and body (flex point)
  3. Loose or corroded connector at the switch or mirror motor
  4. Short to ground or short to power on the switch signal circuit
  5. Failed body control module (BCM) or mirror control module
  6. Blown fuse or poor ground connection for the mirror circuit

How to diagnose and fix it

  1. Verify the fault with a scan tool and check for related codes in the BCM or mirror module
  2. Inspect the power mirror switch connector for corrosion, loose pins, or damage
  3. Test the switch with a multimeter for continuity and correct voltage signals in each position
  4. Check the wiring harness at the door hinge area for chafed or broken wires
  5. Measure resistance and voltage on the switch signal circuit to rule out shorts or opens
  6. If the switch and wiring test good, test the mirror motor circuits and the BCM output
  7. Replace the faulty switch, repair wiring, or replace the BCM as needed, then clear codes and retest

Common misdiagnosis traps for B0102

  • A faulty switch is often replaced unnecessarily when the real problem is a chafed wire in the door hinge boot, which flexes every time the door opens.
  • Intermittent B0102 codes frequently trace to a poor ground connection at the mirror motor or switch, not a failed component.
  • Some vehicles use a serial data message from the switch to the BCM, so a scan tool that reads live switch data is more useful than a simple multimeter.
  • The code can be set by a weak battery or low voltage during cranking, so always check battery health before condemning the switch.
  • Aftermarket mirror replacements with incorrect resistance can trigger B0102 even when the switch and wiring are perfect.

Can I keep driving with B0102?

The vehicle remains safe to drive because the power mirrors are a convenience feature and do not affect steering, braking, or visibility laws in most areas. Avoid adjusting the mirrors repeatedly until the fault is repaired, and manually position them if needed for safe driving.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

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