Module-Front Control: Operation

As messages are sent over the CAN bus circuit, the Front Control Module (FCM) 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 FCM:

1. Air conditioning condenser cooling fan
2. Daytime running lamps - if equipped
3. Fog Lamps
4. Front and rear hazard warning lamps
5. Front turn signals
6. Headlamps
7. Horn
8. Radiator fans
9. Rear window defroster power and timing
10. Stop, turn signal and tail lamps
11. Windshield and liftgate wiper and washer systems

The FCM provides the following features for the above function:

• Acts as a link between the CAN bus network for critical powertrain, anti-lock brake systems, electronic stability program systems and the network for body and interior modules.
• Controls the wipers based on messages on the CAN B bus from the rain sensor module (if equipped).
• Controls the adjustable pedal motor on non-memory equipped vehicles.
• Controls back-up lamps.
• Flashes lamps in response to turn signal, Remote Keyless Entry (RKE) and Vehicle Theft Security System (VTSS) inputs.
• Illuminated approach feature that turns the headlamps on when the vehicle is unlocked with the Remote Keyless Entry (RKE) transmitter.
• Minimizes voltage variations to the headlamps to extend bulb life and to equalize the light output from the lamps, which might otherwise differ due to variations in wiring resistance.
• Monitors battery voltage and turns off non-essential functions such as the fog lamps, rear window defogger, and heated seats if necessary to conserve battery power.
• Operates the high-beam headlamps at reduced intensity by pulse-width modulation of the power supply to provide the daytime running lamps.
• Protects the battery from discharge if the headlamps are left on, by automatically turning them off after eight minutes.
• Provides ambient temperature sensor information.
• Provides A/C pressure transducer information.
• Provides brake fluid level information.
• Provides washer fluid level information.
• Provides the variable delay intermittent windshield and liftgate wiper time delay features, and the vehicle speed sensitive windshield wiper delay variation.
• Sounds the horn in response to RKE and VTSS inputs.
• Turns off the horn in the event of excessively long operation that could otherwise damage the horn.
• Turns off the windshield washer motor after 10 seconds of continuous operation to protect the motor.
• Controls headlamp washers (if equipped).
• Provides wheel speed information on non-ABS equipped vehicles.
• Stores vehicle configuration data.