AutoCodes – GMC – U0128 GMC

U0128 GMC Code - Lost Communication With Park Brake 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 Park Brake Control Module, Park Brake Control Module harness is open or shorted, Park 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: U0128 GMC indicates Lost Communication With Park Brake Control Module.
Common causes: Common causes include Faulty Park Brake Control Module, Park Brake Control Module harness is open or shorted, Park 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 694

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 U0128 GMC 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 Park Brake Control Module has not been received.

OBDII Code U0128 GMC - Lost Communication With Park Brake Control Module - AutoCodes.com — U0128 GMC Code - Lost Communication With Park Brake Control Module

What does this mean?

What are the Possible Causes of the DTC U0128 GMC?

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

How to Fix the DTC U0128 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 U0128 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.

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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 U0128 GMC Code

1. What are the common symptoms of U0128 GMC code?

- Common symptoms include the parking brake warning light being illuminated on the dashboard, limited functionality of the parking brake system, and potential issues with the stability control system.

2. What can cause the U0128 GMC code to occur?

- The U0128 code usually indicates a communication problem between the vehicle's onboard computer and the Park Brake Control Module. This can be caused by damaged wiring, a faulty control module, or a poor connection.

3. How can I diagnose the U0128 GMC code?

- Diagnosing the U0128 code typically involves using a diagnostic scanner to retrieve the specific fault codes stored in the vehicle's computer. Further testing may be required to pinpoint the exact cause of the communication failure.

4. Can the U0128 GMC code be fixed at home?

- While some basic troubleshooting steps like checking for loose connections or damaged wiring can be done at home, resolving the U0128 code often requires specialized equipment and expertise. It is recommended to seek assistance from a qualified mechanic.

5. Is it safe to drive with the U0128 GMC code present?

- Driving with the U0128 code may lead to issues with the parking brake system and stability control, affecting the overall safety and performance of the vehicle. It is advisable to address the problem promptly to avoid potential safety risks.

6. How much does it typically cost to repair the U0128 GMC code?

- The cost of repairing the U0128 code can vary depending on the underlying cause of the communication failure and the labor rates in your area. It is recommended to obtain quotes from multiple repair shops for an accurate estimate.

7. Can resetting the U0128 GMC code make it go away permanently?

- Resetting the U0128 code may temporarily clear the fault code, but if the root cause of the communication issue is not addressed, the code is likely to reappear. It is essential to diagnose and fix the underlying problem to prevent future occurrences.

8. Are there any common tricks to try before taking the vehicle to a mechanic for the U0128 GMC code?

- Checking the parking brake system for any obvious issues, ensuring all connections are secure, and resetting the vehicle's computer by disconnecting the battery for a few minutes are some common tricks to try before seeking professional help.

9. Can extreme weather conditions trigger the U0128 GMC code?

- Extreme weather conditions, such as heavy rain or extreme cold, can potentially affect the electrical connections and components involved in the communication between the vehicle's computer and the Park Brake Control Module, leading to the U0128 code.

10. How long does it typically take to repair the U0128 GMC code?

- The repair time for the U0128 code can vary depending on the exact cause of the communication failure and the availability of parts. In some cases, the repair may be completed within a few hours, while more complex issues may require additional time for diagnosis and repair.