Expedition 4WD V8-4.6L SOHC VIN W (1999)
Suspension Control Module: Description and Operation
NOTE: The 4WAS control module is also used for the RAS system. The internal processor recognizes external circuitry to determine if it is installed
in a 4WAS or a RAS system.
NOTE: The air suspension control module is calibrated with information from the air suspension height sensors. A new or swapped air suspension
control module requires the ride height adjustment calibration process to be performed.
A microcontroller-based electronic air suspension control module controls the air compressor motor (through a solid state relay) and all system
solenoids. The air suspension control module also provides power to front and rear height sensors. The air suspension control module controls vehicle
height adjustments by monitoring the two height sensors, vehicle speed, a steering sensor, acceleration input, the door ajar signal, transfer case signals
and the Brake Pedal Position (BPP) switch. The air suspension control module also conducts all fail-safe and diagnostic strategies and contains
self-test and communication software for testing the vehicle and related components.
The air suspension control module is interchangeable between the RAS and 4WAS system.
The air suspension control module monitors and controls the system through a 32-pin two-way connector. The air suspension control module is keyed
so that it cannot be plugged into an incorrect harness. There are two sides of the harness connection to the air suspension control module. Each is
uniquely colored and keyed to prevent reversing the connections.
