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1999 Grand Cherokee limited v-8 all 4 brakes locked up help

tvan42288tvan42288 Posts: 2
edited April 2014 in Jeep
I have a 1999 Jeep Grand Cherokee Limited with V-8 Qudra AWD. My problem is all 4 brake calipers locked up at same time. ABS and Brake light are out. Vehicle has new Master cyclinder & Resevior(Napa), all 4 new calipers, flushed brake fluid all new. Can't find any air in system. When I release pressue at Master Cyclinder brakes release instanly with vehicle turned off. Is it possible the ABS system is locking the brakes up and keeping the pressure when running?

Thanks for any help or suggestions you can offer.


  • tuggajbtuggajb Posts: 646
    when you replaced the master cyl did you replace boster?
    if so your brake pedel is not returning to full back try and put toe under brake pedal and pull back with tow see if releases brakes if not just loosen master cyl and make sure all stuff was replaced right (push rod master cyl seal ) did the master cyl look like the old one? if not what was changed must not set into boster further than old one as that will not let fluid back into res and lock brakes

    brake pedal dose not have springs to return to top uses boster to do that needs to have no binding where pedal and boster hook together
  • I didn't replace the brake booster as it is not leaking any air. The power part of this seems to be working fine. The master cyclinder & Resevior looked identical. I have to change the Brake light switch under the resevior only. Brake pedal is fine. After the brakes locked up I just release the pressure at the master cyclinder. The front and rear caliper immediatly released. I have tried to rebleed and can't get any air from system. Is is possible the ABS system is not letting the pressure release after time or a valve in the lines some where?

    Thanks for thoughts and help.
  • tuggajbtuggajb Posts: 646
    the only way that pressure is held in is that the brake pedel is not returning to full out
    remove the brake light switch and try to see if you solve the prob if it does it is your brake light switch not installed right as i sead the brake pedal must return to the stop at the off position ifen it dont you do not release the prereeure in master cyl( I think that stop light switch is causing prob)
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