AutoCodes – GMC – U2106 GMC

U2106 GMC Code - Lost Communications With Transmission Control Module

Quick Answer

Modules connected to the Controller Area Network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Common causes include Faulty Transmission Control Module (TCM), Transmission Control Module harness is open or shorted, Transmission 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: U2106 GMC indicates Lost Communications With Transmission Control Module.
Common causes: Common causes include Faulty Transmission Control Module (TCM), Transmission Control Module harness is open or shorted, Transmission 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 1,996

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 07, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U2106 GMC Description

Modules connected to the Controller Area Network (CAN) serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits. The messages are supervised and also, some periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module. A module with a CAN serial data circuits malfunction or which loses power during the current ignition cycle will have a Loss of Communication Diagnostic Trouble Code (DTC) set by other modules that depend on information from that failed module. If any of the CAN circuit are shorted to battery voltage, ground, or between them no communication is possible on the CAN serial data bus, a Diagnostic Trouble Code will set.

OBDII Code U2106 GMC - Lost Communications With Transmission Control Module - AutoCodes.com — U2106 GMC Code - Lost Communications With Transmission Control Module

What does this mean?

What are the Possible Causes of the DTC U2106 GMC?

Faulty Transmission Control Module (TCM)
Transmission Control Module harness is open or shorted
Transmission Control Module circuit poor electrical connection

How to Fix the DTC U2106 GMC?

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 U2106 GMC 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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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 U2106 GMC Code

1. What are the common symptoms of OBDII code U2106 GMC (Lost Communications With Transmission Control Module)?

- Common symptoms include transmission shifting issues, the transmission going into limp mode, and the Check Engine light illuminating.

2. What are some possible causes of code U2106 in a GMC vehicle?

- Potential causes include a faulty Transmission Control Module (TCM), damaged wiring or connectors, a defective CAN bus communication system, or a software issue.

3. How can I diagnose the U2106 code in my GMC vehicle?

- Diagnosing the code typically involves using a diagnostic scanner to retrieve the trouble codes, checking for communication issues between the TCM and other modules, and inspecting the wiring and connectors for any damage.

4. Can I continue driving my GMC with the U2106 code present?

- It is not recommended to drive your vehicle with the U2106 code active, as it can lead to further transmission problems and potential safety issues. It is best to address the issue promptly.

5. What are some repair tips for resolving the U2106 code in a GMC vehicle?

- Repair tips may include checking and repairing any damaged wiring or connectors, reprogramming the TCM if necessary, or replacing the TCM itself if it is found to be faulty.

6. Is it possible to reset the U2106 code in a GMC vehicle without fixing the underlying issue?

- While clearing the code may temporarily turn off the Check Engine light, it will not resolve the underlying communication problem between the TCM and other modules. It is important to address the root cause of the issue.

7. How much does it typically cost to repair the U2106 code in a GMC vehicle?

- The cost of repair can vary depending on the specific issue causing the code. It may range from a simple wiring repair to a more involved TCM replacement, potentially costing several hundred to over a thousand dollars.

8. Can a DIY enthusiast fix the U2106 code in a GMC vehicle?

- Depending on the underlying cause, some DIY enthusiasts may be able to address the U2106 code by checking and repairing wiring or connectors. However, more complex issues may require professional diagnosis and repair.

9. Will the U2106 code cause permanent damage to the transmission in a GMC vehicle?

- Ignoring the U2106 code can potentially lead to further transmission issues and damage if not addressed promptly. It is important to resolve the communication problem to prevent any long-term damage.

10. How long does it take to repair the U2106 code in a GMC vehicle?

- The repair time can vary based on the specific cause of the code and the complexity of the repair. It may range from a quick wiring repair that can be done in a few hours to a TCM replacement that could take longer.