Front Control Module (FCM)

FRONT CONTROL MODULE
The Front Control Module (FCM) is a micro-controller based module located in the left front corner of the engine compartment. On this model, the Integrated Power Module (IPM) must be positioned aside in order to access the Front Control Module. The Front Control Module mates to the Power Distribution Center (PDC) to form the Integrated Power Module (IPM). The Integrated Power Module connects directly to the battery and provides the primary means of circuit protection and power distribution for all vehicle electrical systems. The Front Control Module controls power to some of these vehicle systems electrical and electromechanical loads based on inputs received from hard wired switch inputs and data received on the PCI bus circuit (J1850).

As messages are sent over the PCI bus circuit, the front control module reads these messages and controls power to some of the vehicles electrical systems by completing the circuit to ground (low side driver) or completing the circuit to 12 volt power (high side driver). The following functions are Controlled by the Front Control Module:

- Headlamp Power with Voltage Regulation
- Windshield Wiper "ON/OFF" Relay Actuation
- Windshield Wiper "HI/LO" Relay Actuation
- Windshield Washer Pump Motor
- Fog Lamp Relay Actuation
- Park Lamp Relay Actuation
- Horn Relay Actuation

The following inputs are Received/Monitored by the Front Control Module:
- B+ Connection Detection
- Power Ground
- Ambient Temperature Sensing
- Ignition Switch Run
- Washer Fluid Level Switch
- Windshield Wiper Park Switch
- PCI Bus Circuit

The Front Control Module (FCM) is a printed circuit board-based module with an on-board micro-processor. The Front Control Module interfaces with other electronic modules in the vehicle via the Programmable Communications Interface (PCI) data bus (J1850). In order to obtain conclusive testing the Programmable Communications Interface (PCI) data bus network and all of the electronic modules that provide inputs to, or receive outputs from the Front Control Module must be checked. All PCI (J1850) communication faults must be resolved prior to further diagnosing any front control module related issues.

The Front Control Module was designed to be diagnosed with an appropriate diagnostic scan tool, such as the DRBIII. The most reliable, efficient, and accurate means to diagnose the front control module requires the use of a DRBIII scan tool and the proper Body Diagnostic Procedures.

Before any testing of the Front Control Module is attempted, the battery should be fully charged and all wire harness and ground connections inspected around the affected areas on the vehicle.