AutoCodes – Generic – U189A

U189A Code - DC To DC Converter Control Module 'A' Lost Communication With Hybrid Powertrain Control Module

Quick Answer

Modules connected to the class 2 and high-speed General Motor Local Area Network (GMLAN) serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Hybrid Powertrain Control Module, Hybrid Powertrain Control Module harness is open or shorted, Hybrid Powertrain 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: U189A indicates DC To DC Converter Control Module 'A' Lost Communication With Hybrid Powertrain Control Module.
Common causes: Common causes include Faulty Hybrid Powertrain Control Module, Hybrid Powertrain Control Module harness is open or shorted, Hybrid Powertrain 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 792

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 Jun 09, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U189A Description

Modules connected to the class 2 and 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 Diagnostic Trouble Code (DTC) is reported on a class 2 link to the scan tool by Powertrain Control Module (PCM) even if they may be set by different modules. The DTC will set when a node alive message has not been received from an identified module within the last 5 seconds after establishing class 2 serial data communication, or a supervised high-speed GMLAN message has not been received.

OBDII Code U189A - DC To DC Converter Control Module 'A' Lost Communication With Hybrid Powertrain Control Module - AutoCodes.com — U189A Code - DC To DC Converter Control Module 'A' Lost Communication With Hybrid Powertrain Control Module

What does this mean?

What are the Possible Causes of the DTC U189A?

Faulty Hybrid Powertrain Control Module
Hybrid Powertrain Control Module harness is open or shorted
Hybrid Powertrain Control Module circuit poor electrical connection
Faulty DC To DC Converter Control Module 'A'

How to Fix the DTC U189A?

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 U189A 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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Need more information on how to fix the U189A code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U189A code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

U189A Buick — DC To DC Converter Control Module 'A' Lost Communication With Hybrid Powertrain Control Module
U189A Cadillac — DC To DC Converter Control Module 'A' Lost Communication With Hybrid Powertrain Control Module
U189A Chevrolet — DC To DC Converter Control Module 'A' Lost Communication With Hybrid Powertrain Control Module
U189A GMC — DC To DC Converter Control Module 'A' Lost Communication With Hybrid Powertrain Control Module

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 U189A Code

1. What are common symptoms of OBDII code U189A?

The common symptoms of code U189A may include loss of power steering, illuminated warning lights on the dashboard, and difficulty starting the vehicle.

2. What can cause OBDII code U189A to occur?

Code U189A is typically triggered when there is a communication failure between the DC to DC converter control module and the hybrid powertrain control module, which can be caused by wiring issues, faulty modules, or low battery voltage.

3. How can I diagnose OBDII code U189A?

Diagnosing code U189A involves using a diagnostic scanner to retrieve the fault codes from the vehicle's computer system, checking the wiring and connections between the control modules, and performing a thorough inspection of the DC to DC converter control module.

4. Can I continue driving my vehicle with OBDII code U189A present?

It is not recommended to drive the vehicle with code U189A present, as it can lead to further damage to the control modules and affect the overall performance and safety of the vehicle.

5. How can I repair OBDII code U189A?

To repair code U189A, you may need to repair or replace any damaged wiring or connectors, reset the fault codes using a diagnostic scanner, and ensure proper communication between the DC to DC converter control module and the hybrid powertrain control module.

6. Are there any DIY tips for fixing OBDII code U189A?

While some basic troubleshooting steps can be taken, diagnosing and repairing code U189A may require specialized tools and expertise. It is recommended to consult a professional mechanic for proper diagnosis and repair.

7. Is OBDII code U189A specific to a certain vehicle make or model?

Code U189A is a generic OBDII code that can occur in various hybrid vehicles equipped with a DC to DC converter control module and a hybrid powertrain control module.

8. How serious is OBDII code U189A?

Code U189A should be addressed promptly to prevent further issues with the vehicle's control modules and overall performance. Ignoring this code can lead to more complex and costly repairs in the future.

9. Can a low battery voltage cause OBDII code U189A to appear?

Yes, low battery voltage can contribute to code U189A as it can affect the communication between the control modules. It is essential to ensure the battery is in good condition and properly charged.

10. How long does it typically take to repair OBDII code U189A?

The repair time for code U189A can vary depending on the exact cause of the issue and the complexity of the repair. It is best to consult with a mechanic for an accurate estimate of the repair time.