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Thread: Calling on Teves brakes experts!

  1. #1

    Calling on Teves brakes experts!

    I hope it is not inappropriate for a non-Reatta owner to make an appearance here to seek help regarding the brake system. I just inherited a 1990 Cadillac with minimal mileage (32K miles to be exact), the electric/hydraulic brakes aren't working right however.

    I searched the archives and read through a lot of material on the Teves Mark II system, my symptoms and the context are somewhat different than the norm.

    The car just came out of storage, over 3 years in less than ideal conditions. The brake booster looks brand new, but the pedal is rock hard. With a lot of effort, I will get minimal braking force, although I only pushed the car around, I can't tell how the system behaves at speed. I haven't yet tried to turn the engine (I want to empty the fuel system before this) so the full self-test detailed on reatta.net isn't possible for me at this point. I believe the hydraulic pressure system should be triggered with the key turned to ON, yet it doesn't. I understand that the hard pedal means there is no pressure in the system.

    I unplugged the electric pump and ran 12V into it, I can hear the motor is turning, but I can't be sure it's working normally. My first question is this: when the pump fails, does it normally fail altogether, meaning it stops turning completely?

    I'm tempted to think the problem is electrical (either relay or pressure sensor), but there are so many components to this system I'm at a loss finding out what's bad.

    Suggestions of things to try before I buy an entire used assembly (last resort because mine looks brand new, I'd rather find the one part that's failed) would be greatly appreciated.

    Short of doing the full self-test, any other test I could do to provide more clues?

    Many thanks.
    Last edited by Caddynewby; April 24th, 2010 at 12:21.

  2. #2

    Re: Calling on Teves brakes experts!

    If the pump runs when you supply 12 volts directly then you should check the fuses and relay before going any farther. The pressure switch could also be the problem but the fuse and relay are the easiest to check. The Reatta has three cube relays on the firewall (don't know about Caddy) that are identical. One is for the pump. You can swap them to see if the relay is the problem. You must get power to the pump before you can do any other testing.

    Does the pump ever stop running when you power it directly?

  3. #3

    Re: Calling on Teves brakes experts!

    Quote Originally Posted by Ronnie View Post
    If the pump runs when you supply 12 volts directly then you should check the fuses and relay before going any farther. The pressure switch could also be the problem but the fuse and relay are the easiest to check. The Reatta has three cube relays on the firewall (don't know about Caddy) that are identical. One is for the pump. You can swap them to see if the relay is the problem. You must get power to the pump before you can do any other testing.

    Does the pump ever stop running when you power it directly?
    Hmm, I'll have to check this again. If I remember correctly, I ran power directly into the motor so I suppose it could keep going? Am I right in thinking that the pressure switch shuts power to the motor once a certain pressure is reached?

    Will check fuse and relay tomorrow, if I can find the latter.. I actually looked for it briefly, without success. Is it usually mounted in the engine compartment or under the dash inside the cabin?

    Thanks a lot for the guidance! I will report back.
    Last edited by Caddynewby; April 24th, 2010 at 23:14.

  4. #4

    Re: Calling on Teves brakes experts!

    Quote Originally Posted by Caddynewby View Post
    Hmm, I'll have to check this again. If I remember correctly, I ran power directly into the motor so I suppose it could keep going? Am I right in thinking that the pressure switch shuts power to the motor once a certain pressure is reached?

    Will check fuse and relay tomorrow, if I can find the latter.. I actually looked for it briefly, without success. Is it usually mounted in the engine compartment or under the dash inside the cabin?

    Thanks a lot for the guidance! I will report back.
    You are correct. The pressure switch is what should normally shut off the pump when the proper pressure has been reached. When I asked the question I was asking if sometimes the pump would not run when you applied power directly, which would indicate a defective pump that could have stuck or dirty brushes or other problems. I should have made that clear. BTW, I don't consider myself an expert on the TEVES system. I just try to help out when I can.

    The pump relay on the Reatta is attached to a mounting bracket on the firewall, under the hood. (see photo) If you have three relays the third will be for the fuel pump.
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  5. #5

    Re: Calling on Teves brakes experts!

    As an aside, isn't the third relay on a Reatta for the (optional) sunroof? My 'vert only has two relays on the firewall.
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  6. #6

    Re: Calling on Teves brakes experts!

    Quote Originally Posted by wws944 View Post
    As an aside, isn't the third relay on a Reatta for the (optional) sunroof? My 'vert only has two relays on the firewall.
    That could be true on the '90 model but on my '88 model the third relay is for the fuel pump.

  7. #7

    Re: Calling on Teves brakes experts!

    Negative. Third relay is in 88s and 89s and is for the fuel pump for initial start up. In 90 it was moved inside to the interior relay center by the fuses.

    The sunroof relays are located up by the sunroof motor.

  8. #8
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    Re: Calling on Teves brakes experts!

    if you are running 12 volts to the motor, the pressure switch won't come into play; the motor will continue to run. Normally when the system has lost all its pressure, you can expect the pump to run for about a minute, then shut down.
    I've got '90 eldo with Teves; let me look what the relay layout is...
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  9. #9

    Re: Calling on Teves brakes experts!

    A word of caution about testing the motor:

    If you run the motor by applying 12 volts directly I wouldn't run it too long. If the Teves system does not have a pressure relief valve, the motor could stall under high pressure and possibly burn a spot on the armature.

  10. #10

    Re: Calling on Teves brakes experts!

    Quote Originally Posted by harry yarnell View Post
    if you are running 12 volts to the motor, the pressure switch won't come into play; the motor will continue to run. Normally when the system has lost all its pressure, you can expect the pump to run for about a minute, then shut down.
    I've got '90 eldo with Teves; let me look what the relay layout is...
    Yes, running power directly to the motor was the only method I could think of to check whether the motor is the faulty part (or one of them anyway). Since the pedal is very hard, I'm assuming there is no pressure in the system, so the risk of over-pressurizing the system is fairly low, but I'm not powering the motor for more than a second or two for my purposes.

    I haven't had time to continue testing, if you find where the said relay is on your Eldo, this would be very helpful. I'm pretty positive it isn't on the firewall as it is on the Reatta. Thanks to all!

  11. #11
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    Re: Calling on Teves brakes experts!

    You can run the pump for a minute or two without harm. When the pressure gets 'up there', you can hear the pump load up.
    The eldo has two relays dead center of the firewall. Will have to check the shop manual to see which does which.
    BTW, when pressure is built up, you should have brakes.
    My first suspect AFTER you figure out why the pump doesn't run is the accumulator (round black (or grey) ball next to the fluid tank.
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  12. #12

    Re: Calling on Teves brakes experts!

    OK gents, we're getting somewhere.

    I ran power directly to the motor and got it working fine, I let it run for about a minute. Before that, I measured voltage on the plug going to the motor and got nothing. I then found 2 relays on the firewall in front of the steering wheel, I interchanged them, plugged the motor and turned the ignition: the pump started pressurizing the system and the pedal felt normal. The only bad news (so far that is) is that I had fluid pouring on the ground right under the driver's seat, I suppose the lines are rusted out.

    Based on this, am I right in assuming that the pressure switch is working normally? I'm already positive that the pump itself is running as it should.

    Since I can't tell which relay is good and which isn't, I'll probably replace both for simplicity.

    Once I have lines replaced and front brake parts changed, I'll move on to testing the accumulator and the rest of the system.

    Again, thanks to everyone, indispensable help provided here.

  13. #13

    Re: Calling on Teves brakes experts!

    The fluid may be coming from an over filled brake fluid reservoir. The Teves has to be filled in a specific way.
    - Master Cylinder Reservoir Filling Instructions

    At this point you can't assume the pressure switch is working normal unless you let the pump run long enough to shut the pump off.

  14. #14

    Re: Calling on Teves brakes experts!

    Quote Originally Posted by Ronnie View Post
    The fluid may be coming from an over filled brake fluid reservoir. The Teves has to be filled in a specific way.
    - Master Cylinder Reservoir Filling Instructions

    At this point you can't assume the pressure switch is working normal unless you let the pump run long enough to shut the pump off.
    So much fluid poured out, and so little left in the reservoir that I'm pretty sure it is a puncture in the lines; fluid also poured out when I was pressing on the pedal, but a closer look under the car will tell the story. Thanks for the link, I will need it later on.

    Now, to test the pressure switch, I essentially have to risk frying the pump? Isn't there a device that cuts power to the pump when it over-heats? If not, this will be a anxiety provoking test.. how long should I wait for the pump to stop, assuming the system is completely unpressurized?

  15. #15

    Re: Calling on Teves brakes experts!

    Quote Originally Posted by Caddynewby View Post
    So much fluid poured out, and so little left in the reservoir that I'm pretty sure it is a puncture in the lines; fluid also poured out when I was pressing on the pedal, but a closer look under the car will tell the story. Thanks for the link, I will need it later on.

    Now, to test the pressure switch, I essentially have to risk frying the pump? Isn't there a device that cuts power to the pump when it over-heats? If not, this will be a anxiety provoking test.. how long should I wait for the pump to stop, assuming the system is completely unpressurized?
    If you actually have leaking line you will need to bleed the brake system completely. You need to flush the system as teves is sensitive to old dirty fluid and it should be changed every year or so anyway.

    Again bleeding the brakes on the teves in not done in the normal manner as other brake systems. Instructions can be found on my website for flushing and bleeding the brakes the proper way.

    To determine if the pressure switch is defective, first unplug the connector to the pressure switch. Look around the terminals on the pressure switch for any sign of fluid leakage. If you see any at all there is a good chance the switch is bad. Otherwise, when you have all leaks stopped and the brakes bled, let the pump run with the key on and the engine off. Listen for the pump to start sounding like it is slowing down. Shortly after you hear that sound the pressure switch should shut off the pump. I have not known of a pressure switch failing and keeping the pump running continuously but I guess it is possible.

    how long should I wait for the pump to stop, assuming the system is completely unpressurized?
    Should be less than a minute on a system working properly. You must have all air out of the system for that to be true.

  16. #16
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    Re: Calling on Teves brakes experts!

    I would guess that you have at least a bad rear brake line as from what I remember once you pump the brakes to flush the rear it turns into kind of a siphon and drains the resevoir dry.
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  17. #17

    Re: Calling on Teves brakes experts!

    From another page dedicated to the Teves Mark 2 system:

    The pump motor is protected by an internal thermal switch. If the motor overheats due to prolonged running (20 minutes continuous or so) the thermal switch will open shutting off the motor for 2-10 minutes until it cools down.

    Also of interest:

    The Hydraulic Pump Motor most likely will run since the pressure sensed by the Pressure Switch in the system is probably low (below 2030 PSI)if the car has been sitting a while.


    I understand that the pressure switch will close power on the relay when a certain pressure level is reached, but I'd like to know whether the pump would be triggered if there was no signal coming from a faulty pressure switch? From this quote, it seems to me that the pressure switch must be functional for the pump to engage. What am I missing?

    Source: http://www.albeedigital.com/supercou...bs-system.html

  18. #18
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    Re: Calling on Teves brakes experts!

    I'm not sure you're missing anything. The pressure switch, and ONLY the pressure switch will close the relay that powers the pump.
    If either the switch or the relay stick, the pump will never shut off. If either opens (fails to close when it should), the pump won't run.

    I'm curious how the brake fluid is getting inside the cabin...
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  19. #19

    Re: Calling on Teves brakes experts!

    Quote Originally Posted by harry yarnell View Post
    I'm not sure you're missing anything. The pressure switch, and ONLY the pressure switch will close the relay that powers the pump.
    If either the switch or the relay stick, the pump will never shut off. If either opens (fails to close when it should), the pump won't run.

    I'm curious how the brake fluid is getting inside the cabin...
    No no! There is no fluid getting inside the cabin! The leak is under the car directly under the driver's seat, which must be where the rear brake lines are routed. I understand your curiosity though, that would be very strange!

    Regarding the switch, I have no reason to believe it's not working correctly, but again anything in this system could be faulty because the car has been sitting for years. The only items I can identify positively as working normally are the pump and master cylinder. So, following the logic you provided, if my pressure switch is faulty, it must be stuck open. As suggested, I will open up the connection and look for fluid, but if it looks good, the only test will be to pressurize the system once the brake lines are replaced (hope it's not too big a job).

    I'm almost thinking that I'd rather pay for a new pressure switch than risk frying the pump by testing the existing switch..

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