AutoCodes – Generic – B3885

B3885 Code - Trailer Left Tail Lamp Circuit

Quick Answer

The Trailer Lighting Control Module receives a serial data message from the Body Control Module (BCM) indicating that the vehicle park lamps have been activated. Common causes include Faulty Trailer Left Tail Lamp, Trailer Left Tail Lamp harness is open or shorted, Trailer Left Tail Lamp 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: B3885 indicates Trailer Left Tail Lamp Circuit.
Common causes: Common causes include Faulty Trailer Left Tail Lamp, Trailer Left Tail Lamp harness is open or shorted, Trailer Left Tail Lamp 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 1,810

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 23, 2020

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code B3885 Description

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

OBDII Code B3885 - Trailer Left Tail Lamp Circuit - AutoCodes.com — B3885 Code - Trailer Left Tail Lamp Circuit

What does this mean?

What are the Possible Causes of the DTC B3885?

Faulty Trailer Left Tail Lamp
Trailer Left Tail Lamp harness is open or shorted
Trailer Left Tail Lamp circuit poor electrical connection
Faulty Trailer Lighting Control Module

How to Fix the DTC B3885?

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

B3885 02 Trailer Left Tail Lamp Circuit Short to Ground
B3885 04 Trailer Left Tail Lamp Circuit Open

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B3885 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.

Need more information about the B3885 code?

Need more information on how to fix the B3885 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the B3885 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

B3885 Buick — Trailer Left Tail Lamp Circuit
B3885 Cadillac — Trailer Left Tail Lamp Circuit
B3885 Chevrolet — Trailer Left Tail Lamp Circuit
B3885 GMC — Trailer Left Tail Lamp Circuit

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.

Frequently Asked Questions about B3885 Code

1. What does OBDII code B3885 mean?

B3885 indicates a problem with the trailer's left tail lamp circuit, such as an open circuit, short, or faulty connection.

2. What are common symptoms of the B3885 code?

Common symptoms include the trailer's left tail lamp not working, dim or flickering light, or a warning light on the vehicle's dashboard.

3. What causes the B3885 code to appear?

Possible causes include a burnt-out bulb, damaged wiring, corroded connectors, or a faulty trailer wiring module.

4. Can a blown fuse cause the B3885 code?

Yes, a blown fuse in the trailer wiring circuit can cause this code by disrupting power to the left tail lamp.

5. How do I diagnose the B3885 code?

Inspect the trailer's left tail lamp bulb, wiring, and connectors for damage or corrosion, and check for proper voltage with a multimeter.

6. Is the B3885 code specific to trailers?

Yes, this code specifically relates to the circuit for the left tail lamp on a connected trailer.

7. How do I fix the B3885 code?

Replace any damaged or burned-out bulbs, repair or replace faulty wiring, clean corroded connectors, and check the trailer wiring module.

8. Can I drive with the B3885 code active?

While the vehicle may still be drivable, towing a trailer with a non-functional tail lamp is unsafe and may be illegal.

9. Does the B3885 code always require professional repair?

Not necessarily. Simple issues like a bad bulb or corroded connector can often be fixed by the vehicle owner, but complex wiring problems may require a mechanic.

10. Can a faulty trailer wiring module trigger the B3885 code?

Yes, a malfunctioning trailer wiring module can disrupt the left tail lamp circuit and trigger this code.