Important Information – Used ECMs

• Tested & Verified: Good, tested used electrical components.

• Programming Required: Must be flashed to your vehicle’s specific VIN by a dealer or qualified diesel shop before installation.

• Programming Not Included: Buyer is responsible for all programming.

• Return Policy: Electrical components that have been opened, installed, or plugged in are generally non-returnable unless covered under warranty.

3944124 Used Cummins ISB 5.9L Engine Control Module (ECM) – CM550

This used Cummins 3944124 Engine Control Module (ECM) is designed for compatible Cummins ISB 5.9L diesel engine applications commonly found in school buses, medium-duty commercial trucks, and other diesel-powered vehicles.

The 3944124 ECM is associated with the Cummins CM550 electronic engine control system, used in select earlier-generation ISB 5.9L 24-valve diesel engines. The ECM manages essential engine functions, including fuel injection control, engine timing, sensor inputs, electronic diagnostics, and engine operating parameters.

A tested used Cummins ECM provides a cost-effective alternative to purchasing a new engine control module, helping fleet maintenance departments and diesel repair facilities reduce repair expenses while extending the service life of existing vehicles.

This module must be programmed to the vehicle’s specific VIN and engine configuration before installation. Programming must be performed by a qualified diesel repair facility or authorized service provider with appropriate Cummins diagnostic and calibration equipment.

Important Compatibility Note: Not all Cummins ISB 5.9L engines use the same ECM. Compatibility depends on the original ECM part number, engine serial number (ESN), Cummins Control Parts List (CPL), emissions configuration, and ECM calibration. Verify these details before purchasing.

Part Specifications

OEM Part Number: 3944124
Stock Number: 10E-3944124-STK
Manufacturer: Cummins
Component Type: Engine Control Module (ECM)
Condition: Used – Tested
Engine Manufacturer: Cummins
Engine Model: ISB 5.9L
Engine Configuration: Inline 6-Cylinder Diesel
Engine Displacement: 5.9 Liters
ECM Family: Cummins CM550 / CM550A
Engine Technology: Electronically Controlled Diesel
Typical Engine Generation: Earlier ISB 5.9L 24-Valve Applications
Programming Required: Yes – VIN/ESN-Specific
Programming Included: No
Typical Vehicle Applications: School Buses, Medium-Duty Trucks, and Commercial Chassis

Common Applications

The Cummins 3944124 ECM is associated with select ISB 5.9L diesel engine configurations used in:

• Blue Bird School Buses equipped with compatible Cummins ISB 5.9L engines

• Thomas Built School Buses equipped with compatible Cummins ISB 5.9L engines

• Freightliner FS-65 School Bus Chassis with Cummins ISB 5.9L engines

• Freightliner Medium-Duty Trucks with compatible Cummins ISB engines

• Freightliner MT-Series Commercial Chassis with compatible ISB 5.9L engines

• Other medium-duty commercial vehicles using Cummins CM550 engine control systems

These are potential vehicle applications, not guaranteed direct fitments for every model year or configuration.

Important Compatibility Note: This ECM is generally associated with earlier Cummins ISB 5.9L electronic engine control systems. It should not be assumed compatible with later Cummins CM850, CM2150, or other ECM generations. Confirm the original ECM hardware, ESN, CPL, and engine calibration before ordering.