For the last weeek or so whenever I travel on highway for 15 or more minutes the orange anti-lock light would come on (therefore the ABS does not work).  

The red brake light has never come on before. until yesterday. I was driving it and both the orange and red lights came on so but the brake operation was unchanged (without ABS though) so I drove immediately home (good thing I was close).  turned off the car expecting a major problem. I turned it back on and I didn't have any breaks. The pedal was rock hard as if I had depressurized the system. I then turned it back off and then turned ignition to on position and I could hear the brake pump running except it sounded really weird not like it normally does.  I let it run about 90 seconds or so to see if it would quit but no luck.

I replaced the accumulator with a part Jeff M gave me about 10,000 miles (10 months ago) because the abs light kept blinking.  

I searched the board and on turbogpgarage.com at the diagnosis section. Unless I am misunderstanding the information if I can get the pump to run but it never builds up pressure that means it is the PM III needs replaced?  Well is it possible for the motor to be running but it is not working correctly therefore it does not build up pressure?

Thanks for any advice

The red brake light going out should indicate the system has built at least some preasure, is it on?  I have had intermitent pump running, likely pump relay contacts bad, you may have same issue, If you get brakes working, but pump is just running and running, might just be bad preasure switch, or relay. Without the tools to measure pressure its
just a guess. need more info on how system is or isn't working.

The Red Brake light has never gone off since it came on.  I just went checked the car tonight and the Red brake light is still on but the orange light is now off. However the red light is still on and the pump still runs.  At first it ran about 20 seconds then shut off. Then I pushed on the pedal to see if the brakes had returned but no luck. I then waited about 30 seconds and the pump began running again but the brakes never stared working.

What I mean by the brakes not working is it takes alot of foot pressure to stop the car from a roll. Not drivable.

Where are the contacts that I should try to clean Are they easily accessable?

the is a 30 or 60 amp fuse in the ABS fuse box located between the drivers shock tower and the battery! :drinking:

ok... this may sound really stupid, but if the PM III breaks down as much as you guys say it does. why not gut the system and have regular breaks like any other W-body. I might just be crazy but that makes more sense to me.

Quote from: Drewskieok... this may sound really stupid, but if the PM III breaks down as much as you guys say it does. why not gut the system and have regular breaks like any other W-body. I might just be crazy but that makes more sense to me.

Easier said than done... :roll:

I just had the same problem 2 days ago.  anti-lock light flashing, then intermittant red brake light.   I can here the master cyl pump or whatever pump it is but it sounds week.  I am going to check the relay tonight.  I think i need to bleed the system.  I am sure its never been changed.  LOOK GOOKY!

UPDATE
I cecked the fuses in the panel along the finder (none were bad), cleaned and refastened most wire clips took off resevoir lid and check fluid level. Turned key to on possition and it the motor finally turned on like it used to did not sound funny ran for about 80 seconds and brakes were fully restored without any lights whatsoever. At the time I thought one of the contacts must have been dirty. But today (week later) the exact same problem has returned.

Problem
-Driving and suddenly Red Brake light comes on (STAYS ON).
-Quickly get it home.
-Turn off car. Restart it NO BRAKES takes HUGH amount of force to stop car
-Pumped hard pedal 40 times to releive pressure (if there was some)
-check fluid (OK)
-Turned key to on position.
-Can here pump runnign faintly ever 15 seconds for a second. Sounds like the pump is not working correctly and on top of that is not ruinning long enough to build up pressure.

Accumulator is fairly new
Any Ideas?
How would I check pressure switch? Do I just have to get another one and swap it out? Where is the brake relay? could this cause this problem?

Thanks for any help