Ford Fiesta: Multifunction Electronic Modules / Module Controlled Functions - System Operation and Component Description. Description and Operation

System Operation

Battery Saver

NOTE: Time-out is 60 seconds if the vehicle is in factory mode or in transport mode.

To save battery voltage, the BCM provides automatic shut-off of the courtesy and demand lamps after a time-out period when the ignition is OFF.

For specific information of the battery saver feature for the interior lamps,
Refer to: Interior Lighting - System Operation and Component Description (417-02 Interior Lighting, Description and Operation).

Post Crash Alert Function

The post crash alert is a function controlled by the BCM . If the RCM determines an impact of enough severity (the airbags may or may not be deployed), the post crash alert function activates.

The post crash alert function sounds the horn and flashes the hazard lamps.

The post crash alert function can be turned off by pressing the hazard flasher lamp switch (which may need to be pressed twice).

Field Effect Transistor (FET) Protection

A Field Effect Transistor (FET) is a type of transistor that, when used with module software, monitors and controls current flow on module outputs. The Field Effect Transistor (FET) protection strategy prevents module damage in the event of excessive current flow.

The BCM utilizes a Field Effect Transistor (FET) protective circuit strategy for many of its outputs (such as a turn lamp output circuit). Output loads (current level) are monitored for excessive current (typically short circuits) and are shut down (turns off the voltage or ground provided by the module) when a fault event is detected. A short circuit DTC sets when the fault event occurs.

The circuit remains off until the fault is corrected and the ignition state is cycled off and then back on, the module resets the Field Effect Transistor (FET) protection and allows the circuit to function.

Component Description

Body Control Module (BCM)

The BCM is a multifunction module that requires a PMI when replaced.

Refer to: Module Configuration - System Operation and Component Description (418-01 Module Configuration, Description and Operation).

Remote Function Actuator (RFA) Module

The RFA module is a multifunction module that does not require PMI when replaced.

Refer to: Module Configuration - System Operation and Component Description (418-01 Module Configuration, Description and Operation).