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Engine-Codes – GMC – U0102 GMC

U0102 GMC Code - Lost Communication With Transfer Case Control Module

Quick Answer

The U0102 GMC code indicates that there is a communication issue between the vehicle's engine control module (ECM) and the transfer case control module (TCCM). Common causes include Faulty wiring or connectors between the ECM and TCCM, Defective transfer case control module, Malfunctioning engine control module. 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
U0102 GMC indicates Lost Communication With Transfer Case Control Module .
Common causes
Common causes include Faulty wiring or connectors between the ECM and TCCM, Defective transfer case control module, Malfunctioning engine control module.
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 09, 2024
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Code U0102 GMC Description

The U0102 GMC code indicates that there is a communication issue between the vehicle's engine control module (ECM) and the transfer case control module (TCCM). The transfer case control module is responsible for controlling the operation of the transfer case, which is a critical component in four-wheel-drive and all-wheel-drive vehicles. When communication is lost between the two modules, it can lead to a variety of performance issues and potential safety concerns.

OBDII Code U0102 GMC - Lost Communication With Transfer Case Control Module
U0102 GMC Code - Lost Communication With Transfer Case Control Module

Common Causes of U0102 GMC

  1. Faulty wiring or connectors between the ECM and TCCM.
  2. Defective transfer case control module.
  3. Malfunctioning engine control module.
  4. Corrosion or water damage to the electrical connections.
  5. Software issues or programming errors in the control modules.

Symptoms of U0102 GMC

  1. Difficulty shifting between two-wheel-drive and four-wheel-drive modes.
  2. Illumination of the "Service 4WD" or "Check Engine" light on the dashboard.
  3. Loss of traction or stability when driving in slippery conditions.
  4. Reduced power or performance, especially when accelerating or climbing hills.
  5. Unusual noises or vibrations coming from the transfer case area.

How to Fix U0102 GMC

  1. Perform a thorough inspection of the wiring and connectors between the ECM and TCCM to check for any damage or corrosion. Repair or replace any faulty wiring as needed.
  2. Test the transfer case control module and engine control module for proper functionality. Replace any modules that are found to be defective.
  3. Clear the diagnostic trouble codes from the vehicle's computer system and reset the system to ensure proper communication between the modules.
  4. Test drive the vehicle to verify that the issue has been resolved and that the four-wheel-drive system is functioning correctly.
  5. If the problem persists, consult with a professional mechanic or dealership for further diagnosis and potential repairs.

Cost to Fix U0102 GMC

The typical repair costs for addressing the U0102 GMC code can vary depending on the specific cause of the issue and the extent of the repairs needed. In general, the cost of parts for replacing a transfer case control module or engine control module can range from $200 to $600 or more. Labor costs for diagnosing and repairing the communication issue can add an additional $100 to $300 or more, depending on the complexity of the repair and the shop's hourly labor rates. It's important to note that these are rough estimates, and actual costs may vary based on factors such as location, vehicle make and model, and the technician's experience. It's recommended to obtain multiple quotes from different repair shops to find the best value for your specific situation.

What does this mean?

Tech Notes for U0102 GMC

There is a factory service bulletin for the following GMC models:

2007-2010 GMC Sierra

2007-2010 GMC Yukon Models

2008-2010 GMC Sierra Hybrid

2008-2010 GMC Yukon Hybrid

GMC Factory Service Bulletin OBDII Code U0102

Need more information about the U0102 GMC code?

Need more information on how to fix the U0102 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U0102 GMC code diagnosed by a professional: Find a repair shop in your area

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 U0102 GMC Code

1. What does the OBDII code U0102 mean for a GMC vehicle?

U0102 indicates that the vehicle has lost communication with the Transfer Case Control Module (TCCM).

2. What are the common symptoms of the U0102 code in a GMC?

Symptoms may include inability to shift into 4WD or AWD, a service 4WD warning light, or erratic drivetrain behavior.

3. What causes the U0102 code to appear on a GMC?

Common causes include a faulty TCCM, wiring issues like damaged or corroded connectors, or communication errors in the CAN bus network.

4. Can a dead battery trigger the U0102 code in a GMC?

Yes, a dead or weak battery can cause communication issues between modules, potentially triggering the U0102 code.

5. How do I fix the U0102 code on my GMC?

Inspect and repair damaged wiring or connectors, check the TCCM for faults, and ensure proper power and ground connections to the module.

6. Where is the Transfer Case Control Module located in a GMC vehicle?

The TCCM is typically located under the dashboard, near the driver side, or attached to the transfer case itself, depending on the model.

7. Can I drive my GMC with the U0102 code active?

Driving may be possible, but 4WD or AWD functionality may be compromised, which could impact performance in adverse conditions.

8. How can I test the TCCM when troubleshooting the U0102 code?

You can use a multimeter to check power and ground connections or a scan tool to verify communication with the TCCM.

9. Does the U0102 code always mean the TCCM is bad?

No, the code can also be caused by wiring problems, CAN bus issues, or other module-related faults.

10. How much does it typically cost to fix the U0102 code on a GMC?

Repair costs vary widely but can range from $100 to $800 depending on whether the issue is wiring-related or requires TCCM replacement.

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