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Thread: Abs issues

  1. #1
    Join Date
    Feb 2014
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    rocky point nc
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    Abs issues

    I have a 91 SC 5 speed. Car set a year brake worked great before now pump doesn't run. I have ohm switches checked relay circuit and power to pump all check out. Does this mean I need a new pump. Abs code is 21.

  2. #2
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    Dec 2007
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    Salem OR
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    See:

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

    ... which should help explain what means what when testing.

  3. #3
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    Apr 2002
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    Norcross, GA
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    Whenever the pump won't run it's usually either the anti-lock relay or the pressure switch. If the motor is original and never been serviced then it could be wornout as well. I would replace things rather than test them with a meter. You can test the pump motor by unplugging it and supplying 12 volts to any 2 adjacent pins. It will run backwards but sounds rough that way while the correct direction sounds smooth. I've had to repair 3 ABS brake systems over the last month.
    90 5spd, best ever E.T. 12.250
    best ever 1/4mi speed 112.89 mph
    Current dyno tune 383.54 rwhp 418.88 rwt

  4. #4
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    Feb 2014
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    rocky point nc
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    I have see the article. I have tested each item according to that. I replace the relay 2 years ago but going to do it again. If it's badnim going vaccum booster

  5. #5
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    Apr 2015
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    Maricopa, AZ
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    I just rebuilt my ABS pump motor. Cost a whopping 10 bucks for heavy duty DC motor brushes which I ground down to the correct size. I sanded the exterior motor casing, re-soldered all the connections, cleaned the seating surfaces and put it back together tonight and installed it...works like a charm. It spun up, filled the accumulator and tomorrow is the bleed and test drive. The original brushes lasted 26 years....so not bad for performance of an original part.

    Name:  abs.jpg
Views: 384
Size:  319.3 KB

    The picture doesn't do it justice, I also heat shrinked the connectors and wrapped with electrical tape.

    The entire motor casing was brown rust, I only sanded and wire brushed away the rust, left the pitting so as not to remove too much of the motor housing.

  6. #6
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    Jul 2014
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    Seattle, WA
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    Quote Originally Posted by shawfr View Post
    I just rebuilt my ABS pump motor. Cost a whopping 10 bucks for heavy duty DC motor brushes which I ground down to the correct size. I sanded the exterior motor casing, re-soldered all the connections, cleaned the seating surfaces and put it back together tonight and installed it...works like a charm. It spun up, filled the accumulator and tomorrow is the bleed and test drive. The original brushes lasted 26 years....so not bad for performance of an original part.

    Name:  abs.jpg
Views: 384
Size:  319.3 KB

    The picture doesn't do it justice, I also heat shrinked the connectors and wrapped with electrical tape.

    The entire motor casing was brown rust, I only sanded and wire brushed away the rust, left the pitting so as not to remove too much of the motor housing.
    My ABS quit working for me last week. I had a few moments before it went out where the dash lights would flash at me, so I have assumed it to be a faulty accumulator. Of course, you can't find any accumulators anywhere but one place, and they don't know when the shipment will be in.

    Do you know what would be the best way to test for this might be? I'd like to be sure of my assumptions, thanks.

  7. #7
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    Quote Originally Posted by Mattcomet82 View Post

    Do you know what would be the best way to test for this might be?

    Seen this?

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

  8. #8
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    Jul 2014
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    Seattle, WA
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    Quote Originally Posted by KMT View Post
    Thanks for the link. I performed the troubleshooting steps, and so far the signs point to a bad pump motor. When I turn the key on, the pump does not run. It has 12vdc at the harness connector, so I know it's getting power. The relay has done its job to this point, correct? I followed the next step to test the relay, but if I'm getting 12v at the pump, that seems like a moot point. Could the pressure switch keep the pump from running? I'm just hoping the pump isn't shot.

  9. #9
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    You can swap the relays easy enough to be sure, and if they are original, new ones would be a good investment in any case. A bad pressure switch would cause no power to the pump, but not otherwise fail the pump if it is getting power, I think. I believe there is a process to jumper to the pump here somewhere to check it on it's own.

    About 4 months ago, I had to replace the relay _and_ the switch.

  10. #10
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    Quote Originally Posted by KMT View Post
    You can swap the relays easy enough to be sure, and if they are original, new ones would be a good investment in any case. A bad pressure switch would cause no power to the pump, but not otherwise fail the pump if it is getting power, I think. I believe there is a process to jumper to the pump here somewhere to check it on it's own.

    About 4 months ago, I had to replace the relay _and_ the switch.
    I guess I'll pick up a new relay and pressure switch. I swapped the relay 2 years back, so I know what part # to search for, but I'm coming up empty searching for the pressure switch. I'd rather not pay dealer prices for a switch.

  11. #11
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    So I found this pressure switch, but at $140, I'm not sure I want to put that $$ down unless I know for sure that's the fix. Autozone has cardone reman units for around $450 after core deposit return, so I'm weighing my options.

    http://www.powerbrakeservice.net/maviiandttep.html

  12. #12
    Join Date
    Jul 2005
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    471
    Good evening

    Try the salvage yards. In addition to 1989 - 1992 Thunderbird Super Coupes/1989 - 1990 XR7 Cougars, you can search for 1989 -1991 Lincoln Continental, 1989 - 1991 Lincoln Mark VII, 1986 - 1988 Turbo Coupe with TEVES Anti-Lock brakes. You might want to get a spare accumulator ball (I have been lucky and found later manufactured units), brake pressure switch and the anti-lock/brake relays as future back-ups while you are there.

    Good Luck.

  13. #13
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    Jul 2014
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    Quote Originally Posted by sam jones View Post
    Good evening

    Try the salvage yards. In addition to 1989 - 1992 Thunderbird Super Coupes/1989 - 1990 XR7 Cougars, you can search for 1989 -1991 Lincoln Continental, 1989 - 1991 Lincoln Mark VII, 1986 - 1988 Turbo Coupe with TEVES Anti-Lock brakes. You might want to get a spare accumulator ball (I have been lucky and found later manufactured units), brake pressure switch and the anti-lock/brake relays as future back-ups while you are there.

    Good Luck.
    I've called every salvage yard on car-part.com with a tbird/cougar, and every salvage yard they told me to call. I probably called 30 of them this week. However I was searching for an accumulator ball then...

  14. #14
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    Quote Originally Posted by Mattcomet82 View Post
    So I found this pressure switch, but at $140, I'm not sure I want to put that $$ down unless I know for sure that's the fix. Autozone has cardone reman units for around $450 after core deposit return, so I'm weighing my options.
    I bought mine via ebay - ACDelco 25530882 GM Original Equipment Brake Pressure Warning Switch, $USD122 new shipped - exact connector fit on my '90SC. Also bought the special socket used.

    The A/Z unit supposedly includes an accumulator.

    Remember there are two relays for the ABS, but only one of them actually related to power at the pump.
    Last edited by KMT; 07-22-2016 at 11:28 AM.

  15. #15
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    I put 12v directly to the pump motor, nothing. I'm looking to purchase a reman pump, but those are like unicorns with rainbow spots.

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