AutoCodes – GMC – U1024 GMC

U1024 GMC Code - Lost Communications With Transmission Control Module

Quick Answer

Modules connected to the class 2 serial data circuit 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: U1024 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 1,276

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 Apr 22, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U1024 GMC Description

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message for the state of health monitoring/node alive messages. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. Once an identification number is learned by a module, it will monitor for that module node alive message. Each module on the class 2 serial data circuit is required to send a Node Alive message every 2 seconds. When no message is detected from a learned identification number for 5 seconds, a Diagnostic Trouble Code (DTC) U1024 is set.

OBDII Code U1024 GMC - Lost Communications With Transmission Control Module - AutoCodes.com — U1024 GMC Code - Lost Communications With Transmission Control Module

What does this mean?

What are the Possible Causes of the DTC U1024 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 U1024 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 U1024 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 U1024 GMC Code

1. What are the common symptoms of OBDII code U1024 GMC?

The common symptoms of U1024 GMC include issues with shifting gears, transmission slipping, hesitation during acceleration, and the transmission going into limp mode.

2. What are the possible causes of the U1024 GMC code?

The U1024 GMC code is typically caused by a faulty transmission control module (TCM), damaged wiring or connectors between the TCM and the PCM, low battery voltage, or a communication error between the TCM and other modules.

3. How can I diagnose the U1024 GMC code?

To diagnose the U1024 GMC code, you can use an OBDII scanner to retrieve the code and check for any additional codes that may be present. You can also inspect the wiring and connectors for any visible damage and perform a voltage test on the TCM.

4. Can I still drive my vehicle with the U1024 GMC code?

It is not recommended to drive your vehicle with the U1024 GMC code present, as it can lead to further damage to the transmission and other components. It is best to address the issue promptly to avoid more serious issues.

5. How can I repair the U1024 GMC code?

Repairing the U1024 GMC code involves addressing the root cause of the communication error with the TCM. This may include repairing or replacing damaged wiring or connectors, replacing the TCM if faulty, or addressing any low battery voltage issues.

6. Can a DIYer fix the U1024 GMC code?

While some DIYers may have the skills and tools to address the U1024 GMC code, it is recommended to consult a professional mechanic or dealership for a proper diagnosis and repair. The complexity of the transmission control system may require specialized knowledge.

7. How much does it cost to repair the U1024 GMC code?

The cost of repairing the U1024 GMC code can vary depending on the root cause of the issue and the labor rates in your area. It is advisable to obtain quotes from different repair shops to compare prices.

8. Will resetting the code make it go away permanently?

Resetting the U1024 GMC code may temporarily clear the code, but it will likely return if the underlying issue is not addressed. It is important to diagnose and repair the root cause of the code to prevent it from reappearing.

9. Is the U1024 GMC code specific to GMC vehicles only?

The U1024 code is a generic OBDII code, so it can appear in vehicles from various manufacturers, not just GMC. However, the specific diagnostic and repair procedures may vary depending on the make and model of the vehicle.

10. How long does it typically take to repair the U1024 GMC code?

The repair time for the U1024 GMC code can vary depending on the complexity of the issue and the availability of parts. Simple fixes like replacing a damaged connector may take less time, while diagnosing and replacing a faulty TCM can be more time-consuming.