hard brake pedal

[cmas]

New guy with brake problem. Help, started my 1990 and the brake pedal was hard, and the brakes did not stop with out alot of foot pressure. No lights are on. Any idea what the problem is?

Thanks

Chas

[Ronnie]

Click here and take the "Brake Test" toward the bottom of the page.

Report back here with the results.

[cmas]

Ron

Thanks for the reply, Test results I made many pumps with pedal, lights never came back on. Car runs normal no lights on, but brake pedal is hard and no brake assist.

2.Pedal is hard from first pump, never changes did 30 pumps.

3. 6 seconds red light turns off. 4 seconds yellow dash lightsturn off.

4. 4 seconds pump turns off.

5.pump never goes back on no matter how much I pump the pedal.

6. no difference over the line and will overflow if I continue to pump pedal with cap on.

7.I feel the tap.

Rod Any idea. Feels like fluid is not flowing back to brakes. No warning lights on dash. I statr car and brake light is on then goes off and never reappears even though brake pedal is hard and no stopping power.

Thanks

Chas

[JWC]

I also have this problem but only when it's cold out, the brake test will not do you any good as long as you still have the "hard pedal" I have asked this same question many times on this site and got a lot of replies but none of them helped.

I have a feeling it's the valve body not moving the valve into position causing little to no brake fluid going to the brakes.

After many hours of asking questions and trying to figure the Teves Brake System out this is the conclusion I have come to with my brakes, I'm just confused as to why mine only become hard when it's cold out, even after flushing the entire brake system, and if it does it again in the fall I will replace the whole Teves asm.

[cmas]

JWC

Thanks for the info.

Chas

[Ronnie]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: cmas</div><div class="ubbcode-body">Ron

Thanks for the reply, Test results I made many pumps with pedal, lights never came back on. Car runs normal no lights on, but brake pedal is hard and no brake assist.

---What happened to test #1?

2.Pedal is hard from first pump, never changes did 30 pumps.

---Does the pedal remain hard after sitting overnight BEFORE turning key to on position?

3. 6 seconds red light turns off. 4 seconds yellow dash lights turn off.

4. 4 seconds pump turns off.

---Bad pressure switch could explain these short elapsed times.

5.pump never goes back on no matter how much I pump the pedal.

---Bad pressure switch could explain this.

6. no difference over the line and will overflow if I continue to pump pedal with cap on.

---You need to get the fluid level correct. Get it even with the line so you can continue to pump the pedal.

7.I feel the tap.

---Good

Rod Any idea. Feels like fluid is not flowing back to brakes. No warning lights on dash. I statr car and brake light is on then goes off and never reappears even though brake pedal is hard and no stopping power.

Thanks

Chas

</div></div>

See comment in quote above.

I suspect the pressure switch is bad. I believe it is not allowing the pump to fully pressurize the accumulator before the it turns the pump off. Therefore you do not have enough power assist pressure to help you stop. That would also explain why the pump does not turn back on.

Use the online Field Service Manual to diagnose the pressure switch. It can be found a Reatta.net under Documents. You will need to register to use it.

Let me know what you find.

[cmas]

Ron

Thanks for the info. Test one, after lights go off red and yellow never come back on no matter how much i Pump pedal. I will try the pressure switch info. I will let you know.

Thanks

chas

[cmas]

Ron

I have to go back to square 1, because I not sure the motor noise I hear when I turn the key on is actually the pump running. I disconnected the connectors to master cylinder and I still hear what I thought was the pump. I checked the relay on the fire wall and they engage when I apply 12 volts. I cannot find the pump motor 5 amp fuse or the ebcm fuse,not in either fuse location on each side of the console or under the hood. Can they be under the dASH,DO YOU HAVE ANY IDEA WHERE THESE FUSES ARE LOCATED, I WANT TO CHECK THEM BEFORE I GO FURTHER.THE MORE I THINK ABOUT THE FAILURE, NEVER A BRAKE PROBLEM UNTIL I STARTED CAR AND IT APPEARED AND IT FEELS LIKE VERY BAD MANUAL BRAKES WITHOUT POWER, MUST BE PUMP IS NOT WORKING.

tHANKS

chas

[Ronnie]

<span style="color: #FF0000">Get access to the Field Service Manual as recommended above.</span> You cannot do without it. It will answer most of your questions.

First, you MUST determine if the pump motor is running or not. Disconnect the connector that is on the pump motor to determine if the pump runs or not. The connector has two wires one black and one pink with black strip. IF it is not running check for 12 volts between the two wires referenced above.

Let me know what you find.

Then troubleshoot why it is not running.

[cmas]

RON

THANKS, I DID GET ACCESS TO REATTA.NET.

I DO NOT HAVE 12 VOLTS ON CONNECTOR 2 WIRE BLACK AND PINK STRIPE EITHER SIDE WITH THE KEY ON. I HAVE FOUND A 30AMP FUSE ON THE FIRE WALL AND IT WAS OK. I CANNOT FIND THE TWO 5 HAVE FOR THE RELAYS. REATTA. NET DOES NOT GIVE A LOCATION.

THANKS

CHAS

[cmas]

Ron

I have to go under dash to find other two fuses per reatta net. I will get back to you if the fuses were bad.

[Ronnie]

I don't really suspect the fuse being bad. I'm still thinking pressure switch.

Try this:

Find the brake pump relay on the fire wall it should have a Brown wire and a Gray with Red stripe wire.

Ground the Gray with Red strip wire.

Test for 12 volts at the pump connector.... Do you have 12 volts?

--If YES see if pump will run when connected. Don't let it run long connected like this. Just a test to see if it will run. IF it runs you probably have a bad pressure switch that normally supplies a ground to the brake pump relay Gray with Red stripe wire.

--If NO power to connector, swap the relay temporarily with one of the other two on the fire wall and test connector again for 12 volts. If you now have 12 volts the original relay is bad.

[cmas]

Ron

I swapped relays, no help. I ran 12 v to pump, pump worked,brakes worked fine. I do have 12vt going to the relay and have continuity from line from relay to pump.Tested both relays with 12v and they close. The problem appears to be the relay is not getting a command to close when you turn on the key and not transferring the 12 volts to the pump. Any suggestions?

Chas

[cmas]

Ron

You may be right about the pressure switch, I read that it supplies ground to the relay coil and stops the pump from running by breaking the ground when it hits capacity. Maybe it is not sending the ground to energize the relay. Think I should by a pressure switch or is there a test I could do before.

Thanks

Chas

[Ronnie]

Did you ground the Gray wire with Red strip going to the relay as I suggested? Did the relay pickup and supply 12 volts to the pump? If so pressure switch is almost sure to be the problem.

Your really need the pressure adapter to connect to the brake system to read the actual pressure in the line to know for sure if the pressure switch is good or bad. It should let the pump run until it builds ~2200 psi in the accumulator before turning off the pump (by breaking the ground to the pump relay). I don't have one.

Would be nice if you had a pressure switch that is known to be good to swap to see if it corrects the problem OR a parts store that would let you return it if that is not the problem.

[cmas]

Ron

Thanks, I will ground the gray wire tomorrow and order a pressure switch.

Thanks for all your help, you are a real gentleman!

Chas

[Ronnie]

You are welcome!

Please post here if your problem is solved by this thread so others can benefit from it. Maybe JWC is still monitoring this thread and can get his brakes working by reading this.

[bobwhite]

The location of the pressure switch prevents using a standard socket to remove it. The switch is squeezed into a tight location You have to find a thin wall socket to get it out. Some members have ground down the walls of regular sockets so it would fit.

[JWC]

For what ever reason my brake pedal is only hard in the cold weather, and after the car warms up it's fine, thats why I think it's my valve body with a little bit of water in it, even after I flushed it.

[Guest Misfit]

THE FUSE IS UNDER THE DRIVER SIDE DASH BY THE CENTER CONSOLE

[cmas]

Ron

I was able to get the pressure switch out with an adjustable plier and IT FIXED THE PROBLEM IMMEDIATELY,Thanks to your guidence and expertise.

In summary hard brake pedal,no power brakes, listen for pump working, mine didnot, check voltage to relay on firewall, if not present check 5amp fuses under dash, remove panel under steering wheel replace if bad, mine were fine, next ground grey and purple wire going to relay,did so and pump worked, pressure switch was not sending ground to relay, so it could not close and deliver 12volts to pump.Replaced pressure switch and fixed problem. Thanks to all that responded.

Charlie

[cmas]

Bob

Thanks for the info.

Chas

[cmas]

Jwc

Sounds that you have diagnosed the problem correctly, next time it occurrs,put a pin through the grey and purple wire and ground it and see if the pump works. I purchased my switch ad GmDirect parts for 92.00 plus 20.00 shipping.

Thanks

Chas

[Ronnie]

Glad I could help. I think your problem being solved, by us going through the diagnosis step by step, will help others.

Before I purchased my Reatta, a lot of mechanics had tried to fix the brakes but failed. I knew that I was on my own in fixing my brakes. By using the brake test at Reatta.net and studying the FSM, I leared as much as I could about the brake system. My problem turned out to be a bad accumulator.

Thanks to everyone on this forum who offer your help!

[JWC]

I wish someone could help me fixing my "Hard Brake Pedal" it is only hard when it's cold out, like I said before I have flushed the system and even took it to a dealer and they had no clue. I still think it may be a sticking valve but will have to wait until fall again since it has been fine during the warm months.

[Ronnie]

I'm willing to help when it gives a problem.

[JWC]

Thanks I will get back to this when the weather turns cold