U1879 GMC Code - Drive Motor Control Module 2 Lost Communication With Engine Control Module
Quick Answer
The U1879 GMC code indicates that the Drive Motor Control Module 2 (DMCM2) has lost communication with the Engine Control Module (ECM). Common causes include Faulty wiring or connectors, Software glitches in the modules, Malfunctioning DMCM2 or ECM. 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
- U1879 GMC indicates Drive Motor Control Module 2 Lost Communication With Engine Control Module.
- Common causes
- Common causes include Faulty wiring or connectors, Software glitches in the modules, Malfunctioning DMCM2 or ECM.
- 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.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
Code U1879 GMC Description
The U1879 GMC code indicates that the Drive Motor Control Module 2 (DMCM2) has lost communication with the Engine Control Module (ECM). The DMCM2 is responsible for controlling the electric drive motor in hybrid or electric vehicles, while the ECM manages the engine's performance. When these two modules are unable to communicate with each other, it can lead to a range of issues affecting the vehicle's drivability and overall performance.
Common Causes of U1879 GMC
- Faulty wiring or connectors
- Software glitches in the modules
- Malfunctioning DMCM2 or ECM
- Water or corrosion damage to connectors
- Electrical interference or signal disruption
Symptoms of U1879 GMC
- Reduced power or acceleration
- Hesitation during acceleration
- Poor fuel efficiency
- Stalling
- Dashboard warning lights illuminated
How to Fix U1879 GMC
- Perform a thorough diagnostic scan to identify the specific cause of the communication loss between the DMCM2 and ECM.
- Inspect wiring, connectors, and modules for any visible damage or corrosion.
- Repair or replace any faulty wiring, connectors, or modules as necessary.
- Clear the diagnostic trouble codes from the vehicle's system and retest for proper communication between the DMCM2 and ECM.
- Test drive the vehicle to ensure that the symptoms associated with the U1879 code have been resolved.
Cost to Fix U1879 GMC
The typical repair costs for addressing the U1879 GMC code can vary depending on the specific cause of the communication loss and the extent of the repairs needed. In general, replacing faulty wiring or connectors may cost between $100 to $300, while replacing a malfunctioning module could range from $500 to $1500. Labor costs can add an additional $80 to $150 per hour, depending on the shop's rates and location. It is advisable to consult with a qualified mechanic or dealership for an accurate estimate based on your vehicle's make and model.
Need more information about the U1879 GMC code?
Need more information on how to fix the U1879 GMC code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the U1879 GMC code diagnosed by a professional: Find a repair shop in your area
Frequently Asked Questions about U1879 GMC Code
1. What does OBDII code U1879 mean on a GMC?
U1879 indicates that the Drive Motor Control Module 2 has lost communication with the Engine Control Module (ECM), typically in hybrid or electric vehicles.
2. What are the common symptoms of code U1879 on a GMC?
Symptoms may include reduced engine or motor performance, warning lights such as the check engine light or hybrid system light, and potential loss of regenerative braking.
3. What causes U1879 to appear on a GMC vehicle?
This code is usually caused by issues such as a faulty drive motor control module, a failing engine control module, damaged wiring or connectors in the communication circuit, or software glitches.
4. Can driving with a U1879 code damage my GMC?
It depends on the severity of the communication failure. In some cases, it may lead to limited drivability or reduced performance, so it’s best to address the issue promptly.
5. How do I diagnose a U1879 code on a GMC?
Start by inspecting the wiring and connectors between the Drive Motor Control Module 2 and the ECM. Use a scan tool to check for additional codes and verify the communication status of the modules.
6. Can a software update fix the U1879 code?
Yes, if the issue is related to a software glitch, updating the ECM or Drive Motor Control Module software through the dealership may resolve the problem.
7. Do I need to replace the Drive Motor Control Module for a U1879 code?
Not necessarily. Replacement should only be considered after verifying that the module itself is faulty and other potential causes, such as wiring or software, have been ruled out.
8. How much does it cost to repair a U1879 code on a GMC?
Repair costs vary depending on the cause. Simple wiring repairs may be inexpensive, while module replacements or reprogramming can cost several hundred dollars.
9. Can a weak battery cause the U1879 code on a hybrid or electric GMC?
Yes, a weak 12V auxiliary battery or high-voltage battery issue can disrupt communication between modules, potentially triggering this code.
10. Is U1879 a common issue in GMC vehicles?
This code is less common and typically appears in GMC hybrid or electric vehicles, where multiple control modules must communicate seamlessly.
Discuss the causes and fixes for U1879 GMC OBDII Code
Code U1879 GMC comments
No comments found for this page.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.