I was asking about the ABS light. You mentioned the brake light, but never addressed the ABS light. What is the ABS light doing?

thats what im talking about the light on the dash that says brake 91 does not have a abs light it just says brake

I am pretty sure there is also a yellow/orange ABS light, but given the scope of the issue, I bet it is likely no longer working or has been disabled. That is part of the diagnosis.

In my journeys online, it appears that the Supreme received the Powermaster III Brake system. An all in one Master cylinder/ABS module that uses electrically driven hydraulic assist.

I found a thread on another board that does provide some insight as well as part information.

http://www.w-body.com/showthread.php...utlass-Supreme

Gonna keep reading myself.

im not reading all that but, i had a 88 cs over 220k on it when i got rid of it, a 90 gp over 300k no abs i think my old mans lumi was a 91. none had abs and all i did was the rears had problems so if you get the parking brake working and use it, and the rear sliders working good i always got good pad life. my point is if it where my car i would just go get a regular master and booster from a junkyard and run new lines and be done with it.

has anyone ever installed a hyrdo boost brake system in one of these cars to get past this abs system thats obsolete?

You may have a very simple problem. At the top of the parking brake pedal there should be a plunger switch that detects when the park brake is depressed. Sometimes that switch can be out of position and the plunger is extended simply because it is not in contact with the pedal. This will cause your car to think the park brake is applied when it is not.

Just adjust the position of the switch.