AutoCodes – GMC – P0634 GMC

P0634 GMC Code - Control Module Overtemperature

Quick Answer

The Transmission Control Module (TCM) temperature sensor is located inside of the control solenoid valve assembly which has no serviceable parts. Common causes include Obstructions in the airflow of the radiator or transmission cooler, Kinked or damaged transmission fluid lines, Damage to the transmission cooler. 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: P0634 GMC indicates Control Module Overtemperature.
Common causes: Common causes include Obstructions in the airflow of the radiator or transmission cooler, Kinked or damaged transmission fluid lines, Damage to the transmission cooler.
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 18,041

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 Jul 16, 2022

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
Comments
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Code P0634 GMC Description

The Transmission Control Module (TCM) temperature sensor is located inside of the control solenoid valve assembly which has no serviceable parts. The Transmission Control Module monitors the Transmission Control Module sensor for over-temperature protection. The Diagnostic Trouble Code (DTC) will be set if the internal temperature of the TCM is greater than 142°C (288°F) for 5 s.

OBDII Code P0634 GMC - Control Module Overtemperature - AutoCodes.com — P0634 GMC Code - Control Module Overtemperature

What does this mean?

What are the Possible Causes of the DTC P0634 GMC?

Obstructions in the airflow of the radiator or transmission cooler
Kinked or damaged transmission fluid lines
Damage to the transmission cooler

How to Fix the DTC P0634 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 does this mean?

Code Tech Notes

Check transmission fluid level and condition and replaced fluid if necessary.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0634 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.

Need more information about the P0634 GMC code?

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Need Help with the Code?

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Information for Specific GMC Models

P0634 2014 GMC Sierra — Control Module Overtemperature
P0634 2015 GMC Sierra — Control Module Overtemperature
P0634 2016 GMC Sierra — Control Module Overtemperature
P0634 2017 GMC Sierra — Control Module Overtemperature
P0634 2018 GMC Sierra — Control Module Overtemperature

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.