Brakes

smac

Registered User
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!
 
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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-lock-braking-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
 
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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.
 
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 :eek:. 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 :rolleyes: 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.
 
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?
 
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.
 
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.
 
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.
 
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/showthr...ays-And-what-s-this-(pic)&highlight=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/showthr...-questions&highlight=abs+pressure+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.
 
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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 :p 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. :cool:
 
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?
 
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.
 
Forgive my ignorance: a) how does one jump at a connector, and b) where exactly is the pressure switch connector?
 
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Forgive my ignorance: a) how does one jump at a connector, and b) where exactly is the pressure switch relay?

Sorry, but this might be something you should have someone local do for you. If you're not comfortable with using a jumper wire, you might do more harm than good. I'd hate to see that happen.

Ken
 
Forgive my ignorance: a) how does one jump at a connector, and b) where exactly is the pressure switch connector?
You can use a short piece of insulated wire with about 1/4" striped off on both ends. The pressure switch connector is NOT easy to get to. Look at the diagram of the unit and you'll see a wire bundle connection just above the pump motor. Thats what you need to disconnect.

However, if it were me, I'd only do that after testing everything else I could test first. For instance, you can start with just seeing if you're getting power to the pump motor itself with the key in the run position. That connector is easy to reach; its on the side of the Teves Unit. Its about 1" in diameter, and has 4 wires (2 grey, 2 grey/red) coming out of it. Look at the diagram to see which pins have voltage... So IF it has power and the pump isnt running, then you need go no further.. its the pump motor which has failed. If no power, then test for voltages at the relay connector. There will be at least 2 of those which have 12V. 1 is the relay coil, the other is from the power block. If only 1 has power, then you'll need to test the pressure switch... which means jumpering the connector at the switch.. the one thats difficult to reach.

As a note, if in doubt, its never a bad idea to just replace the relay itself. They aren't that expensive and the contacts do wear out.
 
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So I put the relays back in and tested the four pin connector. Voltage read 10.00 and slowly lowered to 9. I tested again and obtained the same result. I was like, whatever, and plugged the four-pin connector back in AND THE PUMP KICKED ON!!! And the abs light is off. The pump ran for about 20 seconds, the shut off, at which point I turned the key off and performed a mad dance of joy.

So what's next? The brake fluid reservoir is low. I assume because the the pump filled the accumulator...?
 
Now back to square one. Abs and brake light with hard pedal. The only thing that has changed is that I know the pump works. I can hear it most of the times I 'test' the system with the key on. If I pump the brake pedal with the key on I can hear the pump kick on, and after a few pumps of the brake pedal the whole thing has a mental breakdown and both lights come on and the pedal gets hard. I assume the accumulator is at fault, an early diagnosis by someone (can't remember who).

Correct me if I'm wrong here, anyone...
 
Yes; the accumulator is WAY overdue to be replaced. The problem is that used ones are dying due to age; but you may get lucky in the boneyard.

I linked to where Victor lists them, but he's out of stock currently.

RwP
 
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