Circuit Description
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 powertrain control module (PCM) controls fuel delivery and determines fuel system operation on bi-fuel (KL6) vehicles. The PCM is not capable of operating the high current compressed natural gas (CNG) fuel injectors. The 8 PCM injector pulse width modulated (PWM) signals are received by the fuel injector control module (FICM) and duplicate PWM signals are generated by the FICM in order to operate the CNG injectors. Ignition voltage is supplied to the fuel injectors. The FICM controls each CNG fuel injector by grounding the control circuit via a solid state device called a driver. The FICM monitors the status of each PWM input signal. If the control module does not receive a fuel injector PWM signal from the PCM DTC P1020 sets.