Control Module Communications

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The control module system has a computer, the engine control module (ECM), to control fuel delivery, timing, and some emission control systems. The control module system monitors a number of engine and vehicle functions and controls the following operations through the fuel injection control module (FICM):

Fuel rail pressure
Fuel injector
Fuel injector pulse width

The diesel ECM, located in the engine compartment, is the control center of the control module system. The engine control module used on the electronic fuel injected 6.6L diesel is referred to as a ECM.

The ECM constantly looks at the information from various sensors, and controls the systems that affect vehicle performance. The ECM performs the diagnostic function of the system. The ECM can recognize operational problems, alert the driver through the MIL - Service Engine Soon, and store one or more diagnostic trouble codes (DTCs) which identify the problem areas to aid the technician in making repairs. See the specific diagnosis procedure for more information.