Fuel Injector Control Module Description: Notes

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

The fuel injector control module (FICM) is a non-flashable control module that is not capable of serial data communication.

The FICM performs the following tasks:

Operates the CNG injectors based upon the powertrain control module (PCM) injector signals
Supplies the reference, ground and signal circuits to the fuel rail temperature (FRT), fuel tank pressure (FTP) and fuel tank temperature (FTT) sensors
Communicates the FRT, FTP and FTT sensor values to the PCM using a single dedicated PWM circuit
Communicates FICM diagnostic information to the PCM using a dedicated PWM circuit

The PCM controls fuel delivery and determines fuel system operation. The PCM monitors various engine and vehicle functions to provide the correct amount of CNG or gasoline fuel under all operating conditions. The fuel injector control circuits, an AF enable circuit and 2 PWM communication circuits connect the PCM to the FICM. The PCM is not capable of operating the high current CNG fuel injectors. The PCM injector pulse width signals are received by the FICM and duplicate pulse width signals are generated by the FICM in order to operate the CNG injectors. The Bi-fuel vehicles utilize underhood mounted injector relays. When operating on gasoline the injector relays are energized allowing the PCM injector pulse width to go directly to the gasoline injectors.