AutoCodes – Cadillac – U0128 Cadillac

U0128 Cadillac 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 Cadillac 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 2,420

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

What does this mean?

What are the Possible Causes of the DTC U0128 Cadillac?

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 Cadillac?

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 Cadillac 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 Cadillac Code

1. What does the OBDII code U0128 mean on a Cadillac?

The U0128 code means the vehicle's main computer has lost communication with the Park Brake Control Module (PBCM).

2. What are the common symptoms of the U0128 code on a Cadillac?

Symptoms include the parking brake not working, illuminated warning lights like ABS or brake warnings, and potential issues with automatic parking brake release.

3. What causes the U0128 code on a Cadillac?

Common causes include a faulty Park Brake Control Module, damaged wiring or connectors in the communication circuit, or a software issue in the module.

4. Can I still drive my Cadillac with the U0128 code?

Yes, but itâ€™s not recommended as the parking brake system may not function properly, posing a safety risk.

5. How do you diagnose a U0128 code on a Cadillac?

Diagnosis involves checking the wiring and connectors for damage, testing the PBCM for faults, and using a scan tool to check for additional codes and communication errors.

6. How do you fix the U0128 code on a Cadillac?

Repairs may include replacing or repairing damaged wiring, reconnecting loose connectors, reprogramming the module, or replacing the Park Brake Control Module if itâ€™s defective.

7. Can a weak battery cause the U0128 code to appear?

Yes, a weak or failing battery can cause communication issues between modules, potentially triggering the U0128 code.

8. How much does it cost to repair a U0128 code on a Cadillac?

Repair costs vary, but they can range from $100 for simple wiring repairs to over $500 if the Park Brake Control Module needs replacement.

9. Can clearing the U0128 code fix the problem?

Clearing the code may temporarily erase it, but the issue will recur if the underlying problem is not addressed.

10. Is the U0128 code specific to Cadillacs?

No, the U0128 code is a generic communication fault applicable to many vehicles, but the exact diagnosis and repair process may vary by make and model.