Question about 2004 Jeep Grand Cherokee
I've had a soft brake pedal (goes nearly to the floor) that's slowly gotten worse. Replaced Master Cylinder (dealer - twice). Pads and rotors fine, no external leaks. Jeep dealer says HCU (in ABS system) needs replacement. Found one online at 1/2 dealer price. Question is: service procedure says to use Dealer service tool (DRB II) to bleed HCU (which turns on the ABS pump, I think). Can I just hook it (the ABS pump) up to B+? Has anyone else replaced an HCU that would have some tips or cautions? Thanks!!!
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Posted on Jan 02, 2017
First, inspect all lines and fittings for seepage. If fluid is getting out anywhere, air is entering system as well. Fill the master cylinder and bleed it first. Make sure that when bleeding someone is holding pedal down until after you have closed each bleeder screw.(applies to all bleeders). Bleed the right rear, then l/r, r/f then l/f. While doing this keep checking master to make sure it does not run dry at any point. Make sure that at each wheel there is no more air coming out before you continue on to next one. Sometimes if there is an excessive amount of air, it's good to go around to each wheel twice.(use a small box wrench on bleeders if possible so you can actually see what's coming out.(Another way of doing this is to use a small section of plastic tubing like fish tank air hose, and attach it to end of bleeder (sometimes if hose is too small, it can be warmed in hot water so it expands over nipple.) put the free end in a glass jar with some fluid in it, keeping the hose in the fluid to prevent air from entering, using this method abslolutely prevents air from getting into system while bleeding)
Other causes of low pedal are worn rotors or drums and improperly adjusted rear brakes. If you have ABS, all of this applies but there may be a problem with abs system (usually will turn on abs warning light)
Posted on Feb 22, 2009
This may sound dum but its been done a few times and is a simple mistake , the bleeder screw is up top, with the caliper on the bleeder screw should be up top, if not then calipers are on the wrong side, it sounds like air in the system, also you pumped the pedal up to push out the piston so pads hit rotor after bleeding,i dont see anything else, if the pedal is good with pinched lines at caliper then it got to be calipers are wrong or on the wrong side and the bleeder is not atop caliper,also you bleed the rear also? these trucks and cars use left caliper and rt rear on one system of the master and rt front and left rear on one side, let me know about the caliper, heres a picture to show you what i mean. hope this helps
Posted on Nov 16, 2010
Did you bench bleed the master cylinder before you installed it? If not you might beed to pull it off and bench bled it.
Posted on Oct 15, 2012
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