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AutoCodes - Generic - B3891

B3891 Code - Trailer Fog Lamps Circuit

- Code Popularity: 494 Views
- Repair Importance Level: 3/3
- Repair Difficulty Level: 3/3
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What are the Possible Causes of the DTC B3891?

NOTE: The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.
  • Faulty Trailer Fog Lamps
  • Trailer Fog Lamps harness is open or shorted
  • Trailer Fog Lamps circuit poor electrical connection
  • Faulty Trailer Lighting Control Module
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How to Fix the DTC B3891?

Review the 'Possible Causes' mentioned above and visually examine the corresponding wiring harness and connectors. Ensure to check for any damaged components and inspect the connector pins for signs of being broken, bent, pushed out, or corroded.

Code Tech Notes

B3891 02 Trailer Fog Lamps Circuit Short to Ground
B3891 04 Trailer Fog Lamps Circuit Open

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What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B3891 code, it typically requires 1.0 hour of labor. The specific diagnosis time and labor rates at auto repair shops can differ based on factors such as the location, make and model of the vehicle, and even the engine type. It is common for most auto repair shops to charge between $75 and $150 per hour.

What are Code Possible Symptoms?

  • Engine Light ON (or Service Engine Soon Warning Light)

Code B3891 Description

The Trailer Lighting Control Module receives a serial data message from the Body Control Module (BCM) indicating that the vehicle rear fog lamp have been activated. The Trailer Lighting Control Module responds by applying battery voltage to the trailer fog lamp control circuit illuminating the trailer fog lamps. The Diagnostic Trouble Code (DTC) sets when the Trailer Lighting Control Module detects a short to ground or an open/high resistance in the trailer fog lamps control circuit.

OBDII Code B3891 - Trailer Fog Lamps Circuit - AutoCodes.com
B3891 Code - Trailer Fog Lamps Circuit

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Code B3891 comments

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