From Crown Victoria Optional Equipment TidBits
Antilock brakes: optional some years, standard others but delete option avaliable
Retrofit notes: Many parts required including master cylinder, hydraulic control unit (hcu), controller, abs wiring harness, wheel speed sensors, brake hoses, brake line, new front hub assemblies with abs exciter rings and new rear axle shafts that have abs exciter rings on them. Cost of parts is a couple thousand dollars from the ford dealer, not including installation. To further complicate matters, there are several different revisions of the hcu used in crown vics and marquis and they are not interchangeable: 92'-94', 95'-95', 96'-97', 98'-00', 01'-02'
On the topic of wiring for 1995+ crown vics, the abs control module wiring is integrated into the 14290 dash to headlamp harness, but the rest of the wiring is the same between a car that is abs equipped and one that is not. So on a non-abs equipped vehicle, one would not have the electrical connector present to plug in the hcu into, nor would one have the wiring present for the front wheel speed sensors. But the wiring that runs from the rear wheel speed sensors to behind the front passengers side kickpanel would be present. Like the name implies 14290, feeds the lighting on the front of the car, it also contains the abs harness, the underhood fuseblock behind the battery, police power leads, the ambient air temp sensor for the climate control and a few other misc items.
Suggestion: If you want a car equipped with ABS, make sure the vehicle has antilock brakes installed before purchasing. Attempting to retrofit ABS to a non-abs equipped car is very expensive and labor intensive.
Can determine whether vehicle has ABS by lifting hood and looking at routing of brake line, if all the metal lines run from the master cylinder to the large hydraulic control unit towards the front of the engine bay on a bracket mounted to the steering box bolts, the vehicle has abs. If metal brake lines run directly from master cylinder to under frame rails, vehicle does not have ABS. Additionally if car is permitted to be driven, take vehicle to an open area and attempt to lock up brakes. If ABS equipped, the vehicle should not leave skid marks of signifcant length and the characteristic ABS pulses should be felt in brake pedal. Is a saying in the automotive industry: "you only need to use antilock brakes once for the system to more than pay for itself"