AutoCodes – GMC – U179A 2017 GMC Sierra

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

Quick Answer

The serial data circuit is the means by which the devices in the vehicle communicate with each other. Common causes include Faulty Hybrid/EV Powertrain Control Module 2, Hybrid/EV Powertrain Control Module 2 harness is open or shorted, Hybrid/EV Powertrain Control Module 2 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: U179A 2017 GMC Sierra indicates Lost Communication with Hybrid/EV Powertrain Control Module 2.
Common causes: Common causes include Faulty Hybrid/EV Powertrain Control Module 2, Hybrid/EV Powertrain Control Module 2 harness is open or shorted, Hybrid/EV Powertrain Control Module 2 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 144

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Jul 21, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U179A 2017 GMC Sierra Description

The serial data circuit is the means by which the devices in the vehicle communicate with each other. Once the scan tool is connected to the serial data circuit through the Data Link Connector (DLC), the scan tool can be used to monitor each device for diagnostic purposes and to check for Diagnostic Trouble Codes (DTC). When the vehicle is ON, each device communicating on the serial data circuit sends a state of health message to ensure that the device is operating properly. When a device stops communicating on the serial data circuit, for example, if the device loses power or ground, the state of health message it normally sends on the serial data circuit disappears. Other devices on the serial data circuit, which expect to receive that state of health message, detect its absence; those devices in turn set a DTC associated with the loss of state of health of the non-communicating device. A loss of serial data communications DTC does not represent a failure of the devices that contain the stored DTC.

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

What does this mean?

What are the Possible Causes of the DTC U179A 2017 GMC Sierra?

Faulty Hybrid/EV Powertrain Control Module 2
Hybrid/EV Powertrain Control Module 2 harness is open or shorted
Hybrid/EV Powertrain Control Module 2 circuit poor electrical connection

How to Fix the DTC U179A 2017 GMC Sierra?

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 U179A 2017 GMC Sierra 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.

Need more information about the U179A 2017 GMC Sierra code?

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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.