Brake pressure light is flashing and making a hissing sound it stops when i press the brakes on 1989 lincoln town car

The stop lights won't go out until the pedal is depressed, as there is a switch which is activated by the pedal.

A hard brake pedal is probably caused by a defective servo. The hissing noise is probably an air leak in the servo.

Switch the engine on, open the bonnet (the hood..) and see if you can locate the hissing - that'll probably be in the brake servo area.

If you don't know what a brake servo looks like here is a generic image:

the abs light on the dash should come on when the abs is working (emergency braking)if it comes on when braking normally(gently)chances are a sensor is gone(replace in pairs,fronts & rears)
abs stops the wheels from locking up in an emergency brake situation,you will feel the grab-release,grab-release on the brake pedal......

sounds like your brake light switch has gone bad check it out it should be mounted on the brake pedal it probably got stuck and is keeping your brake lights on.

sounds like the brake light switch.

If the vibration occurs when you are driving (moving) then it is probably warped brake rotors. Machining or replacing the rotors should fix the problem. If the problem is occuring when you are stopped then sounds like a vacuum leak having to do with the power brake booster.

Note: Many warped brake rotors are cause by over torqueing the lug nuts. Hammering lug nuts on with a pneumatic air gun has ruined MANY brake rotors. It is a good idea to actually use a torque wrench and tighten lugs to the recommended torque value that is usually listed in the owner's manual.

Hope this helps you.

Bob

YOU HAVE A FAILTY RELAY AND SWITCH IN THE CAR

if brakes work ok leave well alone ,this sounds like an electrical fault that big money to repair.At the end of the day the brakes are failsafe manually operated

could be lighting control module $$$$$$$ @400
it's above brake pedal area under dash. 6 x 4" approx.
Do high beams work? Flash to pass work?

if it's the lighting control module, it will provide a fault code when dealer tests it with NGS testor.


#9 is LCM, bottom left of pic.

This could be caused by the transmission range selector switch on the tranny, no sure how without the wiring diagram, but seems to ring a bell from my 20 years at a ford delaer.

I would say that your problem would be in your headlight switch. Remove and test wire leading to tail lights.