AutoCodes – GMC – U0438 GMC

U0438 GMC Code - Invalid Data Received From Trailer Brake Control Module

Quick Answer

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Common causes include Faulty Trailer Brake Control Module, Trailer Brake Control Module harness is open or shorted, Trailer Brake Control Module 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: U0438 GMC indicates Invalid Data Received From Trailer Brake Control Module.
Common causes: Common causes include Faulty Trailer Brake Control Module, Trailer Brake Control Module harness is open or shorted, Trailer Brake Control Module 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 722

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 Apr 12, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0438 GMC Description

A Controller Area Network (CAN) is a vehicle bus standard designed to interconnect automotive devices without a host computer. Operating information and commands are exchanged among the devices. The devices have programmed information about what messages are needed to be exchanged on the serial data circuits. Some devices are constantly receiving information from other devices through serial data communication network. The invalid data Diagnostic Trouble Code (DTC) will be set when a receiving device detects a discrepancy in the information it receives from the Trailer Brake Control Module causing its integrity to be questioned.

OBDII Code U0438 GMC - Invalid Data Received From Trailer Brake Control Module - AutoCodes.com — U0438 GMC Code - Invalid Data Received From Trailer Brake Control Module

What does this mean?

What are the Possible Causes of the DTC U0438 GMC?

Faulty Trailer Brake Control Module
Trailer Brake Control Module harness is open or shorted
Trailer Brake Control Module circuit poor electrical connection

How to Fix the DTC U0438 GMC?

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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U0438 GMC 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 U0438 GMC code?

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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.

Frequently Asked Questions about U0438 GMC Code

1. What are common symptoms of OBDII code U0438 in a GMC vehicle?

- Common symptoms include malfunctioning trailer brake system, warning lights on the dashboard, and issues with the trailer brake control module.

2. What can cause the OBDII code U0438 to appear in a GMC vehicle?

- The code U0438 is typically triggered by communication errors between the vehicle's main computer and the trailer brake control module.

3. How can I diagnose the cause of the U0438 code in my GMC?

- Diagnosis involves checking the wiring connections between the vehicle and the trailer brake control module, as well as inspecting the module for any physical damage or malfunctions.

4. Can a malfunctioning trailer brake control module cause the U0438 code in a GMC?

- Yes, a faulty trailer brake control module can lead to the U0438 code being triggered in a GMC vehicle.

5. What are some repair tips for resolving the U0438 code in a GMC?

- Repair tips include checking and repairing any damaged wiring, replacing the trailer brake control module if necessary, and ensuring proper communication between the module and the vehicle's computer.

6. Is it safe to drive my GMC with the U0438 code present?

- It is not recommended to drive the vehicle with the U0438 code active, as it indicates a potential issue with the trailer brake system that could affect safety.

7. Can a DIY enthusiast fix the U0438 code issue in a GMC?

- Depending on the underlying cause, some DIY enthusiasts may be able to address the U0438 code by checking connections, replacing components, and ensuring proper functionality of the trailer brake system.

8. How much does it typically cost to repair the U0438 code in a GMC at a mechanic or dealership?

- Repair costs for the U0438 code can vary depending on the extent of the issue, but expect to pay for diagnostic testing, parts replacement, and labor, which could range from a few hundred to over a thousand dollars.

9. Will resetting the OBDII code U0438 in a GMC make it go away permanently?

- Resetting the code may temporarily clear the warning lights, but if the underlying issue with the trailer brake control module is not resolved, the code is likely to reappear.

10. How important is it to address the U0438 code promptly in a GMC vehicle?

- It is crucial to address the U0438 code promptly to ensure the proper functioning of the trailer brake system and overall safety while towing a trailer.