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1990 Ford Thunderbird SC Question: 1990 thunderbird S.C. ABS problem stiff pedal

 

Question

bird90, Ukiah, CA, November 17, 2009, 12:24
 Enthusiast

well i tried to jump the wires from the only 5 pin plug nothing happened fuses are good got new relay.but when i turn the ignition to the on position.it makes a clicking noise like a relay,so i unpluged the pressure switch located in front under the resevor.and then turned key to on position and it made no nosie so could that be the problem..

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  • Medium-star Best Answer
    backyard tech November 17, 2009, 13:31
     Master

    Read and follow these these instruction to the T.

    Vehicle Application: 1990 Ford Thunderbird SC 3.8L

    Customer Concern: The brake pedal is intermittently hard and feels like there is no assist.
    Tests/Procedures: 1. Check the 40 amp ABS MTR fuse of the Power Distribution Box (PDB) for a blown, missing, or poorly connected fuse.

    2. Check the 10 amp ANTI-LOCK fuse of the Primary Junction Block (PJB) for a blown, missing, or poorly connected fuse.

    3. Disconnect the 5-wire antilock brake pressure switch on the ABS pump and motor assembly.

    4. Install a jumper between the Pink/Light Blue (PK/LB) wire and the Grey (GY) wire. If the pump motor runs, replace the pressure switch.

    5. If the pump motor does not run, check the circuits of the pump motor and pump motor relay for proper power input and output to determine if there is a circuit problem, defective pump motor, or defective relay.

    A. The pump motor relay wiring consists of a Tan/Yellow (T/Y) wire which supplies hot-at-all times power from the ABS MTR fuse.

    B. A Purple/Orange (P/O) wire supplies ignition fed voltage from the ANTI-LOCK fuse.

    C. A Grey (GY) wire supplies a ground.

    D. The PK/LB wire activates the relay when the pressure switch closes and grounds it.

    E. The Grey/Red (GY/RD) wire carries power from the relay to the pump motor when the relay is activated.

    F. The pump motor also has two GY wires that supply it ground.
    Potential Causes: Defective ABS Pump Circuit
    Defective ABS Pump Motor
    Defective ABS Pump Motor Relay
    Anti-Lock Brake System (ABS) Pressure Switch — Antilock pressure switch, circuit, or connection.
    Antilock Brake System (ABS) Pressure Switch Circuit — Antilock pressure switch, circuit, or connection.
    Antilock Brake System (ABS) Pressure Switch Connector — Antilock pressure switch, circuit, or connection.
    Open Fuse

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  • Answer #2

    90sc May 12, 2013, 01:50
     Rookie

    i had the same problem and it took many shops to figure it out i'm not sure how to test but the shop that figured it out also told me the part was unavailable but one trip to ford dealership found it for $100 its the break pressure accumulator. its right next to the break fluid reservoir looks like a steel ball the size of softball. i had to go in to ford to m point at part in partsmans computer because he didn't believe there was a break accumulator (because there is the more commonly known air conditioner accumulator. i also had a problem with breaks not working correctly unless ignition key was in sweet spot when not in sweet spot i had no power breaks and radio + other electrical items didn't work this was a free repair at ford because of recall and i'm not the original owner. i hope this helps, JIM

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  • Answer #3

    Fordslut July 18, 2014, 10:43
     Rookie

    Actually had the same issue. Do not go buy parts. Turn your engine off and pump your brakes like 30 times as hard as you can push them. Then take out the 10amp abs fuse from under the dash. Drain or remove any excess brake fluid. All the fluid should be coming back into the resevoir from the accumulator. Drive the car, you will not have brake assist or be able to stop fast so go slow or back and forth in the drive way if you can. It had to be drive so the car realizes the abs is off. Park it. Re-insert the abs fuse.start your car and drive. Your brakes should be reset and back to normal. It may happen again if the vehicle has been driven in a while.

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