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Thread: no brakes!!!!

  1. #1
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    Default no brakes!!!!

    ok experts, on my 88 TC the abs and brake light came on today, stayed on for a few miles, then went off, ( brakes seemed fine) then came back on and a short time after that i have nearly no brakes with a super hard pedal. all while on a road trip on the city highway. white knuck trip home after i verified i had fluid.
    so my electric brake booster must not be working? any ideas on testing procudure? are these known to fail eventually or do i have a relay issue maybe... I see no fuses other than fuse links at the solenoid, and they seem fine. thanks for the help
    -pete
    july/88 turbo coupe auto

  2. #2
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    to me it sounds like a relay issue, the relay is located under the vacuum tree and it is the first relay you will see. I have done away with ABS completely in both of my 88 TC's and gone with a power brake setup. very easy to do and only takes an afternoon if you have access to a good parts car. I recently did mine from an 86 cougar, I took the booster, master, proportioning block and hard lines going from the master to the block plus you will need the one from the block to the drivers front wheel. now if you want to go this route be prepared to change a few fittings and flare some tubing. its really an easy swap. Autozone had all of the fittings I needed and rented the flaring tool to me, just take the block and they should be able to fix you right up.
    1988 Thunderbird Turbo Coupe
    1987 Thunderbird Turbo Coupe
    1983 Thunderbird Turbo Coupe
    1979 Mercury Cougar XR7 302HO

  3. #3
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    Yep, it is a relay that turns on the abs pump. I had the very same thing happen to me while in stop and go traffic (Sevierville / Pigeon Forge , TN). I thanked God that mine was a manual transmission and for giving me diligence in keeping things like my e-brake in proper working order. I was able to drive her home (about 40 miles) using backroads, replace the relay and go on to work and be only about 20 minutes late.

  4. #4
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    is it the same relay that powers the abs and the booster?
    -pete
    july/88 turbo coupe auto

  5. #5
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    You don't have a chassis guy at your shop that goes back that far? Cuz that's your best bet from my POV. Otherwise, here's the diagrams, check your powers and grounds, I know what the salt does here, so check your connectors, too. Suspect the pump or related wiring/components. Your accumulator isn't staying/being charged. Hope this is helpful.
    1988 Thunderbird 5.0
    GT40P, TFS-1, KB domes, 30#, MAF conversion, Explorer GT40 Upper/Lower, Smog delete, Wide Ratio AOD Mod, Unlocked Speedo, 3G Charging System Upgrade, Hi-Torque Mini Starter, 3.73 LSD, BBK 1 5/8 unequal headers, H-Pipe.

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  6. #6
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    Mine was the hydraulic pump motor relay, but like any electrical problem, you need to half split as much as you can and then do a linear trace to find the culprit. As an example, I would check the input to the Hydraulic Pump Motor Relay (T/Y) and the output (GY/R). If the input voltage (T/Y) is not battery voltage check both sides of Fuse Link "S". If Input (T/Y) has battery voltage and the output (GY/R) has battery voltage, then the relay relay is good and the motor itself is the likely culprit. If the input (T/Y) has battery voltage, but the output (GY/R) is not battery voltage, check the relay trigger wire (GY/Y) for battery voltage. If 12 volts, chances are better than average that the relay is bad. If the relay trigger wire (GY/Y) does not have battery voltage, check the ignition switch.

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    wow thanks for the info guys. i was able to locate the relay on the firewall, the 2c013 one . i thumped on that a couple times and it came to life. so i unplugged it and figured out which ones to jumper to bypass the relay. i did that and it started pumping up. so i will look for a new relay tomorrow. what a great forum we have here!
    -pete
    july/88 turbo coupe auto

  8. #8
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    If you "thumped" it a couple of times, then it either has at least some life in it, or the connections to the relay are the problem. Try cleaning the connector contacts and the relay contacts. I wouldn't drive the car with the relay bypassed, as the hydraulic motor is controlled by the anti-lock pressure switch applying the ground to the hydraulic pump motor relay and avoiding over-pressurizing the ABS system, e.g. it turn the pump on when it needs to build pressure and turns it off when pressure is within norms. Bypassing the relay will either blow out the seals in your ABS system somewhere, or burn up the pump. Don't do it... as tempting as it might be, troubleshooting is one thing, bypassing a critical safety system is something else.

  9. #9
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    http://www.turbotbird.com/techinfo/T...7-88%20TCs.htm

    This link has good info/testing procedures.
    1986 Mercury Cougar - 2.3T/T5 swap, TC brakes and suspension and rearend, 3" exhaust, 255 lph fuel pump, Stinger BOV, Gillis MBC @ 18 psi
    2003 Chevy Suburban Z71 - Daily driver
    2015 Chevy Volt - Wife's daily driver

  10. #10
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    Quote Originally Posted by Crazy88 View Post
    If you "thumped" it a couple of times, then it either has at least some life in it, or the connections to the relay are the problem. Try cleaning the connector contacts and the relay contacts. I wouldn't drive the car with the relay bypassed, as the hydraulic motor is controlled by the anti-lock pressure switch applying the ground to the hydraulic pump motor relay and avoiding over-pressurizing the ABS system, e.g. it turn the pump on when it needs to build pressure and turns it off when pressure is within norms. Bypassing the relay will either blow out the seals in your ABS system somewhere, or burn up the pump. Don't do it... as tempting as it might be, troubleshooting is one thing, bypassing a critical safety system is something else.
    oh no, i am not driving it until i can buy a new relay. its 25yrs old, i will change it out, and clean & regrease all connections before installing.
    -pete
    july/88 turbo coupe auto

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