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U179A 2017 GMC Sierra Code - Lost Communication with Hybrid/EV Powertrain Control Module 2

Quick Answer

The U179A diagnostic trouble code (DTC) for a 2017 GMC Sierra indicates that there is a communication failure between the vehicle's onboard computer system and the Hybrid/EV Powertrain Control Module 2. Common causes include Faulty wiring connections or harnesses, Malfunctioning Hybrid/EV Powertrain Control Module 2, Software glitches in the vehicle's control system. 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
U179A 2017 GMC Sierra indicates Lost Communication with Hybrid/EV Powertrain Control Module 2.
Common causes
Common causes include Faulty wiring connections or harnesses, Malfunctioning Hybrid/EV Powertrain Control Module 2, Software glitches in the vehicle's control system.
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.
What is this?
Table of contents Created and updated by William Orellana on Sep 10, 2024
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Code U179A 2017 GMC Sierra Description

The U179A diagnostic trouble code (DTC) for a 2017 GMC Sierra indicates that there is a communication failure between the vehicle's onboard computer system and the Hybrid/EV Powertrain Control Module 2. This module is responsible for managing the hybrid or electric powertrain components of the vehicle, such as the battery, electric motor, and associated control systems. When communication with this module is lost, it can lead to a variety of performance issues and potentially affect the drivability of the vehicle.

OBDII Code U179A 2017 GMC Sierra - Lost Communication with Hybrid/EV Powertrain Control Module 2
U179A 2017 GMC Sierra Code - Lost Communication with Hybrid/EV Powertrain Control Module 2

Common Causes of U179A 2017 GMC Sierra

  1. Faulty wiring connections or harnesses
  2. Malfunctioning Hybrid/EV Powertrain Control Module 2
  3. Software glitches in the vehicle's control system
  4. Issues with the vehicle's communication network
  5. Electrical interference or corrosion in connectors

Symptoms of U179A 2017 GMC Sierra

  1. Check engine light illuminated on the dashboard
  2. Loss of power or reduced acceleration
  3. Reduced fuel efficiency
  4. Inability to start the vehicle
  5. Stalling or rough idle

How to Fix U179A 2017 GMC Sierra

  1. Perform a thorough diagnostic scan to retrieve the specific DTC and pinpoint the source of the communication failure.
  2. Inspect wiring connections and harnesses for any signs of damage or corrosion, repairing or replacing as necessary.
  3. Test the Hybrid/EV Powertrain Control Module 2 for functionality and replace if found to be faulty.
  4. Update the vehicle's software to the latest version to address any potential glitches in the control system.
  5. Clear the DTC and perform a test drive to ensure the issue has been resolved and that communication with the powertrain control module is restored.

Cost to Fix U179A 2017 GMC Sierra

The typical repair costs for addressing a U179A code can vary depending on the specific cause of the communication failure. In general, repairs for issues related to faulty wiring connections or harnesses may range from $100 to $300, while replacing a malfunctioning control module could cost between $500 and $1000. Software updates may be included in the diagnostic fee, which can range from $80 to $150 per hour. It's important to factor in labor costs when estimating the total repair bill, as rates can vary based on the location and type of auto repair shop.

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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 U179A 2017 GMC Sierra Code

1. What does the OBDII code U179A mean on a 2017 GMC Sierra?

The U179A code indicates a "Lost Communication with Hybrid/EV Powertrain Control Module 2," meaning the vehicle's control modules are not communicating properly.

2. What are the common symptoms of the U179A code?

Common symptoms include warning lights on the dashboard (like the check engine or hybrid system warning light), reduced power, poor fuel efficiency, or failure to start.

3. What causes the U179A code to appear?

Possible causes include a faulty Hybrid/EV Powertrain Control Module 2, wiring or connection issues, software glitches, or a failing battery or charging system component.

4. Can a low battery cause the U179A code?

Yes, a low or failing 12-volt battery or high-voltage hybrid battery can cause communication issues and trigger the U179A code.

5. Is it safe to drive with the U179A code active?

It is not recommended to drive with this code active, as it may result in reduced performance or complete loss of power, potentially causing unsafe driving conditions.

6. How do I diagnose the U179A code?

Diagnosis involves checking the wiring and connectors for damage or corrosion, testing the Hybrid/EV Powertrain Control Module 2, and using a scan tool to verify module communication.

7. What tools are needed to fix the U179A code?

You may need a diagnostic scan tool, multimeter, and access to the vehicle's wiring diagrams to properly diagnose and repair the issue.

8. Can software updates fix the U179A code?

In some cases, a software update for the affected control modules may resolve the communication issue.

9. How much does it cost to fix the U179A code?

Repair costs vary depending on the issue, ranging from $100 for wiring repairs to over $1,000 if the Hybrid/EV Powertrain Control Module 2 needs replacement.

10. Can I clear the U179A code without fixing the problem?

Clearing the code without addressing the root cause will only result in the code returning, as the underlying issue remains unresolved.

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