AutoCodes – Generic – B3888

B3888 Code - Trailer Right Turn Signal Circuit

Quick Answer

The Trailer Lighting Control Module receives a serial data message from the Body Control Module (BCM) indicating that the vehicle left or right turn signal lamp has been activated. Common causes include Faulty Trailer Right Turn Signal, Trailer Right Turn Signal harness is open or shorted, Trailer Right Turn Signal 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: B3888 indicates Trailer Right Turn Signal Circuit.
Common causes: Common causes include Faulty Trailer Right Turn Signal, Trailer Right Turn Signal harness is open or shorted, Trailer Right Turn Signal 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 885

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 B3888 Description

The Trailer Lighting Control Module receives a serial data message from the Body Control Module (BCM) indicating that the vehicle left or right turn signal lamp has been activated. The Trailer Lighting Control Module responds by applying a pulsating voltage to the appropriate trailer turn signal lamp through their respective control circuit illuminating the desired trailer turn signal lamp. The Diagnostic Trouble Code (DTC) sets when the Trailer Lighting Control Module detects a short to ground or an open/high resistance in the right trailer turn signal control circuit.

OBDII Code B3888 - Trailer Right Turn Signal Circuit - AutoCodes.com — B3888 Code - Trailer Right Turn Signal Circuit

What does this mean?

What are the Possible Causes of the DTC B3888?

Faulty Trailer Right Turn Signal
Trailer Right Turn Signal harness is open or shorted
Trailer Right Turn Signal circuit poor electrical connection
Faulty Trailer Lighting Control Module

How to Fix the DTC B3888?

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

B3888 02 Trailer Right Turn Signal Circuit Short to Ground
B3888 04 Trailer Right Turn Signal Circuit Open

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B3888 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 B3888 code?

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Need Help with the Code?

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Information for Specific Makes

B3888 Buick — Trailer Right Turn Signal Circuit
B3888 Cadillac — Trailer Right Turn Signal Circuit
B3888 Chevrolet — Trailer Right Turn Signal Circuit
B3888 GMC — Trailer Right Turn Signal 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 B3888 Code

1. What does OBDII code B3888 mean?

Code B3888 indicates a fault in the trailer right turn signal circuit, meaning the vehicle is detecting an issue with the electrical connection for the right turn signal on a connected trailer.

2. What are the common symptoms of code B3888?

Symptoms include the trailer's right turn signal not working, flickering, or staying on, as well as potential warning lights on the dashboard.

3. What causes the B3888 code to appear?

Common causes include a damaged or corroded trailer wiring harness, a blown fuse, a faulty trailer light bulb, or a malfunctioning trailer module.

4. Can I drive with the B3888 code active?

Yes, you can drive, but your trailer's right turn signal may not function properly, which can be unsafe and may violate traffic laws.

5. How do I diagnose the B3888 code?

Check the trailer wiring harness for damage or corrosion, inspect the right turn signal bulb on the trailer, and test the fuses and relays associated with the trailer lighting system.

6. What tools are needed to troubleshoot code B3888?

You may need a multimeter to test voltage, a test light, a wiring diagram for your vehicle and trailer, and a scan tool capable of reading trailer module codes.

7. How can I fix the B3888 code?

Repairs may include replacing a blown fuse, repairing or replacing damaged trailer wiring, cleaning corroded connectors, or replacing a faulty turn signal bulb.

8. Can a faulty trailer module cause the B3888 code?

Yes, a malfunctioning trailer control module can disrupt the turn signal circuit and trigger this code.

9. What should I check first when troubleshooting the B3888 code?

Start by inspecting the trailer's right turn signal bulb and the wiring harness for visible damage, corrosion, or loose connections.

10. Will clearing the B3888 code fix the problem?

Clearing the code without addressing the underlying issue will not fix the problem, and the code is likely to return when the fault is detected again.