AutoCodes – Chevrolet – B3890 Chevrolet

B3890 Chevrolet Code - Trailer Backup Lamps Circuit

Quick Answer

The Trailer Lighting Control Module receives a serial data message from the Body Control Module (BCM) indicating that the vehicle backup lamps have been activated. Common causes include Faulty Trailer Backup Lamps, Trailer Backup Lamps harness is open or shorted, Trailer Backup Lamps circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: B3890 Chevrolet indicates Trailer Backup Lamps Circuit.
Common causes: Common causes include Faulty Trailer Backup Lamps, Trailer Backup Lamps harness is open or shorted, Trailer Backup Lamps circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 682

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Mar 24, 2020

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
Comments
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Code B3890 Chevrolet Description

The Trailer Lighting Control Module receives a serial data message from the Body Control Module (BCM) indicating that the vehicle backup lamps have been activated. The Trailer Lighting Control Module responds by applying battery voltage to the trailer backup lamp control circuit illuminating the trailer backup 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 backup lamps control circuit.

OBDII Code B3890 Chevrolet - Trailer Backup Lamps Circuit - AutoCodes.com — B3890 Chevrolet Code - Trailer Backup Lamps Circuit

What does this mean?

What are the Possible Causes of the DTC B3890 Chevrolet?

Faulty Trailer Backup Lamps
Trailer Backup Lamps harness is open or shorted
Trailer Backup Lamps circuit poor electrical connection
Faulty Trailer Lighting Control Module

How to Fix the DTC B3890 Chevrolet?

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

What does this mean?

Code Tech Notes

B3890 02 Trailer Backup Lamps Circuit Short to Ground
B3890 04 Trailer Backup Lamps Circuit Open

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B3890 Chevrolet code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.