Expedition 4WD V8-281 4.6L SOHC (1998)
Suspension Control Module: Description and Operation
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 of the vehicle and related components.
The air suspension control module is mounted in the passenger compartment inside the instrument panel, above the radio and temperature controls. 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.
NOTE:
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The 4-Wheel Air Suspension (4WAS) control module is also used for the Rear Air Suspension (RAS) system. The internal processor recognizes
external circuitry to determine if it is installed in a 4WAS or a RAS system.
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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 performs
