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Thread: 90 SC brakes not working

  1. #1
    Join Date
    Apr 2018
    Location
    North Bay, Ontario
    Posts
    6

    90 SC brakes not working

    1990 SC 5 speed, lost brakes last night, pump not running. Accumulator had stored pressure, but still a hard pedal. At this point I am confused to the issue as I had accumulator charge. Has power to the pump motor.

    Anything I should be looking at in specifics? I've seen topics on hard pedal, and I swapped the whole unit with a working spare but no brakes with charge in the accumulator has me stumped. So situation is now no charge (as I let the stored pressure out thinking I had none) and pump not running with power to the motor. Possible pressure switch failure or delay perhaps?

    Thanks!

  2. #2
    Join Date
    Dec 2007
    Location
    PNW
    Posts
    6,455
    • Accumulator
    • Pressure switch
    • Relay(s)
    • Pump motor
    • Lack of fluid
    • Air in line at the master cylinder after having it apart...best to bench bleed, I think, search here for details
    • Failing/failed multi-wire ignition switch down on the right side of the steering column - this one got me just a few months ago.



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

  3. #3
    Join Date
    Apr 2018
    Location
    North Bay, Ontario
    Posts
    6
    Accumulator is good, tested with my spare, was bench bled and tested, no air in system, fluid up to level when checked yesterday with accumulator charged, I guess may be pressure switched as accumulator wasn't discharging fluid pressure to the system when brakes applied. Pump tests ok (disassembled assembly today and applied voltage to verify and motor seems strong).

    Just never had brakes fail with a charged accumulator before.

  4. #4
    Join Date
    Jul 2010
    Location
    Peterborough Ontario
    Posts
    147

    No power assist

    If you have power to the motor, that eliminates
    the pressure switch, relay & power supply(s)
    It has to be a bad motor/pump assy if its not running

  5. #5
    Join Date
    Dec 2007
    Location
    PNW
    Posts
    6,455
    Quote Originally Posted by Tunevo View Post

    Just never had brakes fail with a charged accumulator before.
    I noticed in your other thread you finally determined it was the pump motor.

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