B3890
Trailer Backup Lamps Circuit
B3890 is an OBD-II diagnostic trouble code meaning: Trailer Backup Lamps Circuit. Common causes: broken or damaged wiring harness, poor contact in connectors. Estimated repair cost: $22–111.
Symptoms
- Trailer tail lights do not work
- Trailer rear lights flashing
- Error message on the dashboard
Causes
- Broken or damaged wiring harness
- Poor contact in connectors
- Rear light relay malfunction
- Problems with the trailer control module
How to Fix
- Check the integrity of the trailer wiring harness
- Inspect connectors for oxidation or damage
- Check the taillight relay
- Diagnose the trailer control module
Related codes
Error B3890 by Vehicle Brand
FAQ
What does the B3890 code mean?
B3890 is an OBD-II diagnostic trouble code that indicates: Trailer Backup Lamps Circuit
What causes a B3890 error code?
The most common causes of B3890 include: Broken or damaged wiring harness; Poor contact in connectors; Rear light relay malfunction; Problems with the trailer control module.
How do I fix a B3890 diagnostic trouble code?
To fix B3890: Check the integrity of the trailer wiring harness. Inspect connectors for oxidation or damage. Check the taillight relay. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with B3890?
Limited driving only, diagnose soon
How much does it cost to fix B3890?
The estimated repair cost for B3890 is $22–111. Actual cost depends on your vehicle, location, and labor rates.
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