AutoCodes – Generic – P2550

P2550 Code - Torque Management Request Input Signal 'B' Low

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: P2550 indicates Torque Management Request Input Signal 'B' Low.
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.

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Code Popularity 8,011

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 18, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P2550 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 P2550 - Torque Management Request Input Signal 'B' Low - AutoCodes.com — P2550 Code - Torque Management Request Input Signal 'B' Low

What does this mean?

What are the Possible Causes of the DTC P2550?

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 P2550?

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 P2550 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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Information for Specific Makes

P2550 Buick — Torque Management Request Input Signal 'B' Low
P2550 Cadillac — Torque Management Request Input Signal 'B' Low
P2550 Chevrolet — Torque Management Request Input Signal 'B' Low
P2550 Dodge — Torque Management Request Input Signal 'B' Low
P2550 Ford — Torque Management Request Input Signal 'B' Low
P2550 GMC — Torque Management Request Input Signal 'B' Low
P2550 Lincoln — Torque Management Request Input Signal 'B' Low
P2550 Mercury — Torque Management Request Input Signal 'B' Low
P2550 Pontiac — Torque Management Request Input Signal 'B' Low

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.