AutoCodes – GMC – P2644 GMC

P2644 GMC Code - Torque Management Feedback Signal 'B' High

Quick Answer

To improve shift feel, the Transmission Control Module (TCM) may request that the Engine Control Module (ECM) reduce engine torque during shift events. Common causes include Faulty Engine Control Module (ECM), Faulty Transmission Control Module (TCM), Engine Control Module (ECM) software update. 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: P2644 GMC indicates Torque Management Feedback Signal 'B' High.
Common causes: Common causes include Faulty Engine Control Module (ECM), Faulty Transmission Control Module (TCM), Engine Control Module (ECM) software update.
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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 1,427

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 Jan 23, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P2644 GMC Description

To improve shift feel, the Transmission Control Module (TCM) may request that the Engine Control Module (ECM) reduce engine torque during shift events. When such a request is received, the ECM responds by retarding the base ignition timing and notifying the TCM that the request has succeeded. If the ECM is unable to comply with the request, the ECM sends the TCM a message that the request has failed.
The torque reduction request is sent to the ECM through a communication network called the controller area network (CAN). Two circuits are used to communicate CAN data between the ECM and TCM.
A fault in the CAN will not cause the ECM to set the Diagnostic Trouble Codes (DTC). If a CAN fault occurs, other DTCs will set before this code.
The ECM set the OBDII code when the TCM receives a torque reduction failure message from the ECM.

OBDII Code P2644 GMC - Torque Management Feedback Signal 'B' High - AutoCodes.com — P2644 GMC Code - Torque Management Feedback Signal 'B' High

What does this mean?

What are the Possible Causes of the DTC P2644 GMC?

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

How to Fix the DTC P2644 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 P2644 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 P2644 GMC code?

Need more information on how to fix the P2644 GMC code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P2644 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 P2644 GMC Code

1. What are the common symptoms of OBDII code P2644 in a GMC vehicle?

- Common symptoms include rough idling, poor engine performance, reduced fuel efficiency, and illuminated Check Engine light.

2. What causes the Torque Management Feedback Signal 'B' High code in a GMC vehicle?

- The P2644 code is often caused by a malfunctioning torque management feedback signal circuit, issues with the electronic control module (ECM), or a faulty oil pressure switch.

3. How serious is the P2644 code in a GMC vehicle?

- While the vehicle may still be drivable with the P2644 code, it is important to address the issue promptly to prevent potential damage to the engine or transmission.

4. Can I continue driving my GMC vehicle with the P2644 code present?

- It is not recommended to drive the vehicle extensively with the P2644 code present, as it can lead to reduced engine performance and potential long-term damage.

5. How can I diagnose the P2644 code in my GMC vehicle?

- Diagnosing the P2644 code typically involves using an OBDII scanner to retrieve the code, inspecting the torque management system components, and testing the oil pressure switch.

6. Are there any DIY repair tips for fixing the P2644 code in a GMC vehicle?

- DIY repair tips include checking and replacing the oil pressure switch, inspecting wiring for damages, and resetting the ECM to see if the code reoccurs.

7. Will resetting the ECM clear the P2644 code in a GMC vehicle?

- Resetting the ECM may temporarily clear the code, but if the underlying issue causing the P2644 code is not fixed, it is likely to reappear.

8. Is it necessary to replace the oil pressure switch to fix the P2644 code in a GMC vehicle?

- In many cases, replacing the oil pressure switch resolves the P2644 code; however, it is recommended to thoroughly diagnose the issue before replacing any components.

9. How much does it cost to repair the P2644 code in a GMC vehicle at a mechanic or dealership?

- The cost of repairing the P2644 code can vary depending on the labor rates and parts needed, but it generally ranges from $100 to $300 for parts and labor.

10. Can the P2644 code be a recurring issue in GMC vehicles?

- Yes, if the root cause of the P2644 code is not properly diagnosed and repaired, it can recur intermittently, causing ongoing issues with engine performance and reliability.