AutoCodes – Chevrolet – U0129 Chevrolet

U0129 Chevrolet Code - Lost Communication with Brake System Control Module

Quick Answer

Modules connected to the high speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Brake System Control Module, Brake System Control Module harness is open or shorted, Brake System 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: U0129 Chevrolet indicates Lost Communication with Brake System Control Module.
Common causes: Common causes include Faulty Brake System Control Module, Brake System Control Module harness is open or shorted, Brake System 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 4,450

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 01, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U0129 Chevrolet Description

Modules connected to the high speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. The supervision time-out period is 250 ms. Each message contains the identification number of the transmitter module. The Diagnostic Trouble Code (DTC) sets when a periodic message from the Brake System Control Module has not been received.

OBDII Code U0129 Chevrolet - Lost Communication with Brake System Control Module - AutoCodes.com — U0129 Chevrolet Code - Lost Communication with Brake System Control Module

What does this mean?

What are the Possible Causes of the DTC U0129 Chevrolet?

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

How to Fix the DTC U0129 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U0129 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.

Frequently Asked Questions about U0129 Chevrolet Code

1. What are the common symptoms of OBDII code U0129 in a Chevrolet related to lost communication with the Brake System Control Module?

- Common symptoms include the illumination of the ABS warning light, traction control light, and possibly the check engine light. Additionally, you may experience issues with the ABS system, traction control system, or brake system functionality.

2. What are the potential causes of OBDII code U0129 in a Chevrolet indicating lost communication with the Brake System Control Module?

- The code U0129 can be triggered by issues such as a faulty Brake System Control Module, damaged wiring or connectors in the communication network, a blown fuse, or a software glitch in the vehicle's control module.

3. How can I diagnose the cause of OBDII code U0129 in my Chevrolet related to lost communication with the Brake System Control Module?

- Diagnosing the issue involves using a diagnostic scanner to retrieve the specific trouble code, checking the condition of the wiring and connectors related to the Brake System Control Module, and performing a thorough inspection of the module itself.

4. Can I continue driving my Chevrolet with the U0129 code indicating lost communication with the Brake System Control Module?

- It is not recommended to continue driving the vehicle when this code is present, as it can affect the functionality of critical safety systems like ABS and traction control. It's advisable to address the issue promptly.

5. How can I reset or clear the U0129 code in a Chevrolet after fixing the communication issue with the Brake System Control Module?

- After repairing the communication problem with the Brake System Control Module, you can reset the code using a diagnostic scanner. This will clear the code and turn off the warning lights on the dashboard.

6. Is it possible to repair the communication issue with the Brake System Control Module in a Chevrolet without professional help?

- While some basic checks like inspecting wiring connections can be done by DIY enthusiasts, diagnosing and repairing complex issues related to the Brake System Control Module often requires professional expertise and specialized tools.

7. Are there any common repair tips for addressing the U0129 code indicating lost communication with the Brake System Control Module in a Chevrolet?

- Ensure all wiring and connectors related to the Brake System Control Module are securely connected and free of damage. Checking for blown fuses and performing a software update may also help resolve the communication issue.

8. How much does it typically cost to repair the U0129 code related to lost communication with the Brake System Control Module in a Chevrolet?

- The cost of repair can vary depending on the exact cause of the communication issue. It may involve replacing the Brake System Control Module, repairing wiring, or addressing other underlying problems. Costs can range from a few hundred to over a thousand dollars.

9. Can extreme weather conditions or water damage contribute to triggering the U0129 code in a Chevrolet?

- Yes, extreme weather conditions or water damage can potentially cause corrosion or short circuits in the wiring connected to the Brake System Control Module, leading to communication failures and the triggering of the U0129 trouble code.

10. Will fixing the U0129 code in a Chevrolet related to lost communication with the Brake System Control Module improve the overall safety and performance of the vehicle?

- Yes, resolving the communication issue with the Brake System Control Module is crucial for maintaining the proper functioning of safety systems like ABS and traction control. Addressing the U0129 code will help ensure the safety and performance of your Chevrolet on the road.