Diagnostic Aids
WARNING: This page is about a different car, the 2003 Ford Pickup, 2003 Ford F550 Super Duty, 2003 Ford F450 Super Duty, 2003 Ford Excursion, and 2003 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
The Fuel Injector Control Module (FICM) requires a 12-volt power source. The FICM receives power from the vehicle batteries through the FICM relay contacts each time the ignition is turned on. The PCM communicates with the FICM utilizing CAN protocol. The CAN protocol is an ISO standard for serial data communication. The CAN standard includes a physical layer using differential transmission on a twisted pair of wires and a data link layer that defines a few different message types, arbitration rules for bus access and methods for fault detection and fault confinement.
The PCM monitors the communication circuits to the FICM for an open or short circuit.