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Thread: Brakes

  1. #1
    Join Date
    Jan 2016
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    89

    Brakes

    Car is an 89 SC. For the last few thousand miles, if I hit the brakes with any decent amount of pressure, even just tapping them, the brake light and abs light would come on momentarily. I thought, oh well, I'll get around to finding out what it is sooner or later. Well, as I pulled out of the parking lot from work, both lights came on and stayed on. Crap. About 150 feet later I almost died in an intersection because, well, surprise surprise, the brakes don't work well! The brake pedal is firm, requiring a lot of effort to depress. There's no 'give' to them. Just really hard to push down. I know what air in the lines feels like cuz I've had that issue in an 81 Skylark that my dad and I bled the lines on. This is a different feeling, much like the way the brakes feel after you pump the about 15 times when the car's off. Real stiff. I checked the fuse box and the abs fuse is perfectly fine. I looked at the brake pedal equipment up behind the dash and it's all good. I looked at the brake lines and there aren't any leaks. I looked all around and under the brake fluid reservoir and abs gadgetry below, and there aren't any leaks. There's a lot of moisture now, due to yours truly accidentally overfilling the reservoir because the fluid was low. Very low. I thought, what's to hurt by topping it off and pumping the brakes 150 times. Which I did. Needless to say, I topped it off a little too much and when I went to pump them...yeah. Also, when I turn the key to the 'two-clicks-forward/accessory-mode/on-position', whichever terminology is preferred, there's not the familiar sound of a little pump running and gradually winding down. Before this...episode...I'd turn the key to to 'on' position and hear this pump. If I tapped the brakes, I'd hear it again. It lasts around four seconds, maybe a bit longer. One more thing: my brakes don't squeak, unless I barely touch them, due to a slightly warped rotor.

    So here's a breakdown:

    ABS light on
    Brake light on
    Brake pedal stiff/very little give
    Fuses fine
    Brake pedal equipment fine
    Low brake fluid (before I attempted to top it off)
    No leaks around the brake fluid reservoir
    No leaks around any of the brake lines
    No pump sound in the 'key on' position
    Car had brakes done at 69k, now has 136k

    Just want a thought or two from all the experts before I give in to the temptation to throw $$$$ in black saleen speedstar rims, big brake upgrades, and 93+ hubs/spindles at my car, which I'd love to do but probably won't anyway. Thanks guys!
    Last edited by smac; 04-29-2017 at 03:01 PM. Reason: Forgot to say what year the car is.

  2. #2
    Join Date
    Jan 2010
    Location
    Bossier City, LA
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    Your Teves Mk II Integral ABS isn't running.

    This is probably due to the relay failing, caused by the pump motor running too much, caused by the accumulator ball failing.

    Duffy's tome on these brakes is a great starting point - here's one link:

    http://www.sccoia.org/articles/anti-...raking-system/

    Note: Also, there's a LOT of articles on the ABS system on the earlier SCs here. Toss it to Google, and let it find the articles for you.

    RwP
    Last edited by RalphP; 04-29-2017 at 03:36 PM. Reason: Added note to using Google to search for ABS problems on the form.

  3. #3
    Join Date
    Jan 2016
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    89
    So how does one change/replace the accumulator, hydraulic pump motor relay, and pressure switch? By process of elimination, it is most likely one or more of these. This article was immensely helpful, by the way.

  4. #4
    Join Date
    Dec 2007
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    By process of elimination, it is most likely one or more of these
    I did a write up on the accumulator:
    http://www.sccoa.com/forums/showthre...ht=accumulator

    Be sure the pump is working first.
    Last edited by KMT; 04-30-2017 at 10:31 AM.

  5. #5
    Join Date
    May 2002
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    Dallas, TX
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    5,648
    Be aware that your Teves II unit has a thermal cutoff switch. When the pump motor runs excessively, it can overheat which can cause a fire hazard . So they equipped it with a thermal switch that stops the pump motor until it cools off. That can take a few minutes or an hour or more. If you find the brakes start working again, thats usually the reason for it.

    The thing to do is replace the accumulator, and cross your fingers and hope that the motor didn't wear down the brushes from the overuse. Otherwise, it will eventually need to be replaced. Its a crap shoot finding a good used pump motor. Some of us even rebuild/repair the ones we have.
    I've done that a dozen times or more and from my experience, I'll offer this guidance.... consider going with conventional brakes instead LOL..

    The hydro-boost master cylinders look like a great long term solution, however, they aren't that cheap.

  6. #6
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    Jan 2016
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    Alright, guys. Thanks for the help so far. I feel like my nuts-and-bolts mechanic skills could get me through this one. I'll start with the accumulator. Does anyone know where I can find one without ordering the whole dang assembly?

  7. #7
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    Bossier City, LA
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    Quote Originally Posted by smac View Post
    Alright, guys. Thanks for the help so far. I feel like my nuts-and-bolts mechanic skills could get me through this one. I'll start with the accumulator. Does anyone know where I can find one without ordering the whole dang assembly?
    Currently unavailable new; you might get lucky at the boneyard, though.

    http://spinningwheels-sc.com/hydacaccumulatorballs.aspx

    RwP

  8. #8
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    Apr 2002
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    Madison, Ohio
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    Starting with the accumulator isn't going to find your problem. The immediate problem is that the pump doesn't run so you need to figure that one out first. Start with the relay as it's the most common problem, but a pump not running can be caused by a bad ignition switch, pressure switch, or the pump itself. Once you have the pump working again, then replacing the accumulator will help to ensure this doesn't happen again right away or in short order.
    Quote Originally Posted by Miller View Post
    Ya thats why i tape mine down. People think its bc i dont have a moonroof seal (which is true) but its really to keep my roof from ripping off .
    Email me here.

  9. #9
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    Another common solution is just to delete the ABS and convert to traditional vacuum assist brakes. There is lots of information on the swap in these forums.
    Quote Originally Posted by Miller View Post
    Ya thats why i tape mine down. People think its bc i dont have a moonroof seal (which is true) but its really to keep my roof from ripping off .
    Email me here.

  10. #10
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    Jan 2016
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    I was just about to post saying I should to more processes of elimination to find what was causing the pump to not run. So with the relay, how to I access it? Should I try to pull the whole setup? I'd rather not if I can help it. I do have the shop manual for the car, for what it's worth.

  11. #11
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    Salem, OR
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    The relay(s) are on the pass. side of the firewall, behind the wheelwell hump. There is a group there, including an A/C bypass relay on some cars, so you will see either 2 or three there.

    See http://www.sccoa.com/forums/showthre...ight=ABS+relay

    Search here on the process to jumper at the pressure switch connector to test.

    Example thread (there are others):
    http://www.sccoa.com/forums/showthre...re+switch+test

    Multi-wire ignition switch is inside the dash/kick-panel, right side of the steering column. Check to see if it is starting to open up. Replace if old.
    Last edited by KMT; 04-30-2017 at 10:37 AM.

  12. #12
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    Before you get too far along, jump in the seat, turn off your radio, A/c, and any accesories so that you can hear, and turn the key on. Listen for the sound of the pump running. If you hear it, wait and see if the lights go out. If you don't hear it, then proceed with trouble shooting.

    What my esteemed collegues have over looked is the cycling of the thermal switch. Lets rule that out first.

    2nd thing that has been overlooked is the ignition switch itself. If its loose, the pump motor can also fail to run. You can test that by rocking the key back and forth slightly and listening.

  13. #13
    Join Date
    Jan 2016
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    89
    So I pulled the abs relay and the pump relay. They both look to be covered in a crusty gold/green residue. Can't tell if this is corrosion or not. The female part of each relay is most encrusted. Also, I looked at the four-pin plug. It seems to be fine (at least it LOOKS fine). I assume that before I replace the relays I should test at the four-pin plug to see if there's any current? What tester would I need for this tes?

  14. #14
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    Quote Originally Posted by smac View Post
    So I pulled the abs relay and the pump relay. They both look to be covered in a crusty gold/green residue. Can't tell if this is corrosion or not. The female part of each relay is most encrusted. Also, I looked at the four-pin plug. It seems to be fine (at least it LOOKS fine). I assume that before I replace the relays I should test at the four-pin plug to see if there's any current? What tester would I need for this tes?
    I think the usual test, at least what's worked for me more than once, is to jumper at the pressure switch connector.

    To test for current, you can use a test probe with a light, or a volt meter.

    Corrosion is green, usually - get a strong flashlight and take a close look...scrape a bit off if you can to see if it's just connector grease, just remember if it's just pale yellow gunk on the plastic, it's most likely connector grease applied at the factory. Corrosion, if a factor would be mainly on the metal tangs on the relays. Failure is usually burnt relay points, inside the relay shell, where you can't see it.

  15. #15
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    Forgive my ignorance: a) how does one jump at a connector, and b) where exactly is the pressure switch connector?
    Last edited by smac; 04-30-2017 at 09:56 PM.

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