Hard brake pedal/dash brake light on.

[Notplayn]

I believe in coincidence but I am not so sure I did not cause this. This problem started after I over filled the master cylinder. I topped it off with out pumping the brake pedal and when I did it blew out around the reservoir lid. Is it possible to have damaged the master cylinder internally, say blew out a seal or something that could have set all this in motion. When I removed the brake pressure switch I found brake fluid inside the plug part (in the connector under the weather seal). I also found brake fluid inside the connector on the booster pump (connector that points toward the front of the car). When I found this I thought to myself, this fluid I am seeing is probably spilt from when it blew out. But how did it get behind the rubber seal on both the connectors.............hum. Anyway thanks for your time.
-Update, I tried a different pressure switch and nothing has changed. Pedal hard a brick and not stopping car.

 

[V8Assassin]

Had the exact same problem on a low mile 87 GN. Pedal was hard as a brick, would stop car, but felt like Fred Flintstone brakes. We ended up having to replace the entire powermaster unit. Would have gone to vacuum brakes, but was trying to keep completely original.

 

[turbojd]

I would try and replace the accumulator, usually when that starts to go you will see the brake light in the dash light up and soon after that, a hard brake pedal.

 

[dz28]

Agreed, I ordered the accumulator and will put that puppy on this weekend when I get back to Detroit... thanks for all the input...

 

[Boston GN]

Same symptoms as mine and it was the pump. Although, I drove around for a couple years before deciding to fix it. My right leg was twice the size of my left, haha

 

[zeus87gn]

Hard pedal feel is typically the acc.
The seals in the electrical connectors (plugs) are not water tight. The fluid could have gotten in there from the spray depending on where it went and if the bowl cover popped off. The m/c should not be internally damaged because of overfill.

There are many variables at work in this one.
Will the motor pump at all?
If so, how long does it take until it stops?
Were there any external leaks or problems before this occurred?
How many miles on the unit?
Condition of fluid?

Lots to consider.......

 

[Notplayn]

I replaced the accumulator about 4 years ago and the car for the most part sits. I can not get the motor to pump. I have pumped the brakes with the key on and off, I cant the pump to make a noise. No leaks before. The car has just over 30k on it. I assume it is original. Fluid could stand to be changed.

 

[zeus87gn]

If the motor is not running, you need to check your 30A fuse.
If it is blown, you need to clean (dry) the contacts in all that were wet.
Clean and dry the unit as a whole so you can watch for any future leaks.
Replace the fuse, pump down your acc and be sure your ps bowl is full.
Turn on the key and see if the motor runs.
If it does, you may be good to go (except for thie possible bad acc).
If not, you need to start looking at the wiring or the motor.

 

[1 QWIK 6]

Cardone brake units and parts might be hard to get for a few months, so I was told. My hard pedal was a bad accumulator new fixed it right up.

 

[Notplayn]

zeus87gn, you were right on mark...it was the fuse. I changed it, the pump cycles and no dash brake light. The beer is on me

 

[zeus87gn]

Sounds like a winner but....you need to time your P/M. That fuse blew for a reason. There are other items on the circuit, but the pump motor is the largest current draw. If it times out and doesn't give you any more problems, you are lucky.

Do you know the timing procedure?
Here are the basics: Powermaster Diagnostics