What a great question! My source for information only goes back as far as 1992 ,pretty sure the systems are the same. I'll attach info from the manual that may help you with your problem.It sounds as though you are quite knowledgeable and can read this and understand it better than I can tell you what to look for. Let me know if you need more or different info and good luck!
1992 Town Car/Crown Victoria/Grand Marquis
Suspension, Computer Controlled
The rear air suspension is an air-operated, microprocessor-controlled, suspension system which replaces the conventional rear coil spring suspension and provides low spring rates for improved ride and automatic rear load leveling. It is standard equipment on the Lincoln Town Car.
Two air springs replace the conventional steel springs and support the vehicle load at the rear wheels. The air springs are mounted onto the axle spring seats and to the frame upper spring seats, similar to the conventional rear steel spring system.
The system is operational in the ignition RUN position and has limited operation for one hour after ignition is turned to OFF. The air suspension switch, located on the right side of the luggage compartment, must be turned off when the vehicle is on a hoist, being towed or jump started.
The Air Suspension warning indicator is located in the instrument panel, to the right of the speedometer. The warning indicator flashes five times and then stays on when service switch is turned OFF or a system malfunction is detected.
The rear leveling system operates by adding or removing air in the springs to maintain the level of the vehicle at a predetermined rear suspension "D" ride height dimension, and is controlled by a microcomputer module.
The rear air suspension system module also controls the electronic variable orifice (EVO) steering. Refer to Section 11-02A for Description and Diagnosis of the EVO steering system.
Air required for leveling the vehicle is distributed from the air compressor to the air springs by a nylon air line which runs from the compressor dryer through a Y-fitting to each individual air spring.
|Item ||Part Number ||Description ||Item ||Part Number ||Description|
|1 ||— ||Compressor Relay Power Junction Block ||9 ||— ||From Compressor|
|2 ||— ||Air Line (Attached to Brake/Fuel Bundle) ||10 ||— ||Y-Fitting|
|3 ||3B484 ||Air Compressor With Regenerative Air Dryer and Vent Solenoid ||11 ||— ||To RH Air Spring|
|4 ||— ||Air Line To Compressor ||12 ||— ||Heat Shield|
|5 ||— ||System On/Off Switch ||13 ||— ||Spring Retainer Clip|
|6 ||— ||System Diagnostic Connector ||14 ||— ||Air Springs With Integral Solenoid|
|7 ||— ||Quick Connect ||15 ||— ||Rear Height Sensor|
|8 ||— ||To LH Air Spring || || || |