ok have an 89 xj with a 4.0 had to slam on the brakes the other day due to some jerk pulling out in front of me at the last minute. The brake light came on so I checked the brake system and the lines were good no leaks, pads and rotors looked good, hoses were fine. I did notice loss of fluid in front portion of master cylinder checked drums noticed rear wheel cylinder passenger was leaking so did drum overhaul this past weekend and replaced everything. Still have brake light now my ebrake hasn't worked for sometime now could this be it I have to replace the cables. If not does anyone have any ideas and what would cause this light to come on. I'm not losing any fluids by the way. Thanks for any help

 

Two things come to mind.

Your rear brake shoes need to be adjusted.

I bet your master cylinder is leaking internally.

 

^^^ This ^^^

OK, so you have replaced everything in the rear drums. BOTH sides I hope.
Now you still have questionable front brakes and a suspect master cylinder.
Time to finish the job with fresh front calipers, pads, hoses and new m/c.

 

Do the shoe adjustment for sure first. The "brake" light coming on signifies loss of hydraulic pressure like a master cylinder.

 

I agree with crusier54 that the master cylinder is suspect and could have been weak before the violent braking event. Jamming the brakes on with large force could have finished it off.

Adjusting the rears will hopefully clear up your E-brake operation concerns. I would also check that your drums are not beyond minimum thin, especially if you had them turned. Too thin of drums would mean too much travel needed for good breaking and E-brake operation.

My mind also jumps back to the mechanicals of the rear drum setup from when I recently did mine. I have been a VW/Porsche/Audi guy for decades and the XJ is one of the few domestic and only Chrysler project I have worked on. I found the rear drum setup to be a little funky compared to what I am used to, with the press in pins and E-brake setup with the short cable from the adjuster, around the pivot/rocker to the top spring mount. I did one side at time and was glad to have the other side and the Haynes manual as templates to figure out how it went back together. If something slipped out of place or was re-assembled wrong, the brakes could function and the E-brake not function.

The big question that comes to mind is, did you bleed the whole system or just the rears with the wheel cylinder replacements?

I think you should also look at a full system bleed as part of your trouble shooting. Brake fluid is cheap and is often overlooked. Even without air in the system the fluid is in need of flushing if it is over 3yrs old.

 

Rockauto.com shows a Wagner Re-Man Master Cylinder for an 89 XJ 4.0L for only $12.60 w/no core. Kinda hard to go wrong with a quality brand like Wagner for that kind of money, if the Master Cylinder is what ends up being the culprit.

In typical Rockauto fashion, it showed limited quantity of "Only 2 left" at that price.

 

I did bleed the whole system but will probably replace the master cylinder

 

I thought the rear shoes self adjusted while backing up. Also could the power brake booster be bad someone told me on hard stops that seal could go bad.

 

everything on the front looks fine and the only place for loss of fluid was in the front reservoir of master cylinder (the smaller one) which correct me if I'm wrong that goes to the rear brakes

 

Stay on track here for a minute. Self adjusting brakes rarely work. Adjust the rear brakes. Replace the master cylinder. Under $50 new. No rebuilts.

 

Ok sounds good will give it a shot this weekend already have the master ordered thanks for the help

 

Ok so I got side tracked these past weekends putting brakes on her jetta and working on the clutch of my wrangler. I replaced the master cylinder last night on the cherokee, but the brake light is still on. The only thing I didn't do yet is bleed the brakes after replacing the master cylinder, which I'm waiting for my friend to come over so I can. Can me not bleeding the brakes yet cause the light to still be on

 

not sure about on jeeps but I know for sure On older chevys. after this same headache!

to start with first check to see if you have adequate vaccum running to you brake booster! if that checks out then check your proportioning valve!

Again not sure about jeeps, but I wouldnt figure there much different there is a sensor that is activated when to much pressure, or to little is being used is a braking sequence.

There should be(if they are the same as GM) a little rod on the front part covered by a small rubber boot(looks like a nipple) take the rubber boot off to expose the piston that activated the light. sometimes they get corroded and become lodged. take a c clamp or something and gently squeeze the rod back in. the light will go off.

Again this is from experience with a 81 C10. which showed the brake light was on and all if was was a bad proportioning valve. which on them years are not replaceable(the dont make em anymore) jeeps may vary. either way check you proportioning valve. it should be right under the master cylinder.

 

ok just went and looked at the proportioning valve on my 01. on mine. there is indeed the rubber tip on the front. it does look a little different than the GM one I mentioned though. mine also has a bright orage plastic square behind the plug.

Also right under the fluid resivoir for your brake fluid there is a connection for the proportioning valve. plug that connector, clean in up and put some diletric grease on it. might just be corroded.

hope that helps man.

 

I had the same problem with my 89 cherokee. I replaced the master and booster. And both rear wheel cylinders. My light never turned off till I adjusted the rear brakes.