[ZJPunk98]

Hi guys,

I run a Vanco PBS upgraded front system with EBC pads and rotors all around. Recently, one of my front calipers froze and i replaced it. Prior to the caliper replacement i was getting uneven braking from right to left in the front. I noticed the front right was braking more and heating up a lot compared to the left. Also the braking was soft.

Now: new calipers up front (L and R), the braking feels more even but somewhat soft. I have bleed the lines several times. Sometimes but rarely, the ABS will activate when I come to a complete stop.

could there be air in the abs system or master cylinder? or is the master cylinder going bad? How do i test?

[1stblack97ZJ]

PM SnowLeopard.

there is some sort of electronic bleeding that has to be done that he found out about.

[ZJPunk98]

Originally Posted by 1stblack97ZJ

PM SnowLeopard.

there is some sort of electronic bleeding that has to be done that he found out about.

i will thanks. Nice avitar

[1stblack97ZJ]

Originally Posted by ZJPunk98

i will thanks. Nice avitar

thanks man one of my favorite movies of all time.

[Obie95Sahara]

Could you post up any info that you find? I had the same exact issue, now my abs light is constantly on. I must've bled the brakes about 8 times.. I'd PM him also, but I don't want to bother him with the same question. If you could post back, I'd really appreciate it Thanks alot!

[BlackDaddyZJ]

you have to bleed the abs system. i know you can access it with a DRBIII scan tool, im not sure what other scan tools have that access to it, as ive only ever used a DRBII and DRBIII but ive only come across it on the DRBIII

[1stblack97ZJ]

here is the post by SnowLeopard:

Originally Posted by SnowLeopard

I've discovered something today much to my chagrin. I had no idea the true depth of how ZJ brakes work. Unfortunately folks, simple old-school bleeding is not enough. And now I have the solution to why our brakes can suck more than they have to. For over 4 years now that I've had my current Jeep I've struggled with terrible braking. The pedal travel would be to the point of halfway down before I'd get any real braking. I'd have to be at 3/4 pressed down just to stop for regular stops like red lights and stop signs. I knew that something was wrong. I'd been in other Jeeps, ZJ's among them, that had such better brake response. I could get mine to respond by really pressing down hard. Emergency stops were possible. But...that is beside the point. Braking was not what it should have been.

I even went so far as to upgrade my brakes. I purchased Stillen front rotors, Performance Friction front pads, and Stillen Metal Matrix rear pads from Kolak a year and a half back now. The braking did NOT improve. What the heck? I followed the procedure to seat the surface. It still made no real difference. I've had the brakes bled at least twice by the shop that I went to at the time, in the years leading up to then. No, I didn't do it myself. I think sometimes we forget on JF that a lot of people aren't mechanically inclined, and sometimes work and life responsibilities take priority over working on the Jeep. So my ignorant tail was going to a shop then, too. I do what I can on my own, and I can do more now than I could back then. That's all an aside though.

Back on topic, back in December of 2009 I had my ABS light come on, which it occasionally did, and then eventually would go off after a couple start-ups. I took it to Meineke to get it checked out. I was tired of this brake stuff, and that was the nearest shop. Their diagnosis, I had some really great, upgraded brakes, nothing seemed wrong, but the scan tool said my ABS pump circuit wasn't functioning properly. They cleared it, and it came back. Well, I couldn't get it replaced at $800. So I just figured, the brakes are good, they reiterated that, which worked to corroborate what I'd been told before by 'professionals.' Trusting this, I went on with my day. The ABS light went off the next day, but I took it to the new shop, which I still go to(where the lift was installed), and had them check it over. I was hoping they might find something the Meineke guys missed, or perhaps be able to find a solution that didn't require an $800 part. JY anyone? Of course, trusting a JY ABS pump is another subject entirely.

According to the owner of the shop, a friend of mine which I've known for years(who worked at the previous shop I'd gone to before he opened his own and had bled the brakes for me before), my ABS light wasn't coming on now. He'd gone out and tested the Jeep, and the ABS was functioning properly. There were no codes coming up. So he said the brakes seemed fine. Perhaps the pump was just getting stuck sometimes, as that can happened when they age, apparently. I don't know. I haven't got a PhD in Jeep braking! You just tend to trust someone that does this for a living.

It all simmers down to this very enlightening truth. No one knows ANYTHING about Jeeps. These people are good with GM, Toyota even, who knows? But Jeeps...not a clue!

Surprisingly, most shops out there, including brake specialty shops, have no idea about this basic necessity. Now I reveal it to those of you who might not have ever heard it before...

"There is an automated ABS bleeding procedure that must be performed using a scan tool. Also, it must be performed before you then do the manual brake bleeding."

As quoted from another website; http://jeep garage.org /showpost.php?p=281811&postcount=10
(You'll have to copy and paste that into your browser, then delete the spaces in the URL. JF is censoring the link for some reason as if it's profanity, and I can't get it to work.)

Guess what no one had ever done before. You've got it! No one had EVER followed the basic ABS bleeding procedure using the scan tool. Today I went to the local Jeep dealership and explained my dilemma. That's where I found out about this. In 15 minutes the shop manager test drove my Jeep, with me in the passenger seat, said he didn't like how the brakes felt. He also noted the ABS light lit, which has happened OFTEN since the lift. Braking dynamics change with lifting, and a different COG, I guess. With more strain on the brakes, the ABS issue was cropping up more often. Well, the manager ran the ABS through diagnostics, noted the "ABS pump circuit not functioning correctly" reading, cleared the code, did the ABS prime/bleeding procedure, and voilà, the brakes were working! I was stoked!

The difference is night and day, and I honestly had trouble finding information about this procedure online. Perusing various forums, including JF, I read about a lot of methods of bleeding and a lot of ways to improve Grand Cherokee braking, but never did I read about this. I would definitely have your Jeep looked at if I were any of you who think your ZJ or WJ brakes suck. The pedal feel is soooo much better, and down travel is minimal before they grab. They're still not sports car brakes, and even with my upgraded front rotors and pads they take some pressure to stop, but I mean it's something else. To spend 4 years with cruddy brakes and hundreds of dollars trying to get them working right, only now to realize you have to find the right person who knows what they're doing. Jeeps are entirely different beasts. No one out there knows crud. It's sad. Don't ever assume people will have a clue just because they have tech sewn onto their shirt.

Get your brakes looked at. They will work without this done, but they will work sooo much better if it's taken care of. Only, I came home after work to find the thread I linked to. It says afterward you're supposed to manually bleed the brakes. So I'm going to take care of that ASAP to ensure the best braking possible. Never take your braking for granted. Brakes are probably the most important part of your Jeep.

My only issue now is that the ABS light came back on when I came home from work. I think that the improper bleeding in the past, leaving the entire braking system not functioning right, has done irreparable damage to the pump. It works, but either the pump itself or the electronics are not quite right. I know I don't need them, but here's something else that's awesome.

ABS on our Jeeps...doesn't suck as much as we thought. The symptoms where my pump activates and I feel the jitter of "OMG I can't stop now because the road is slightly uneven or has some rocks on it!" are gone. I can actually go onto a gravel road and slam on the brakes without that instantaneous loss of braking that I had before. The ABS still works(whenever the light isn't popping on), but it isn't overactive like it always had been, what I thought was natural for these Jeeps. It's smarter than I knew. It just was confused before due to the improper servicing of the past.

I'm irked that the pump is going out, and I'd like to have properly functioning ABS as it's good in a lot of situations. I don't plan on running anything bigger than 31's on my ZJ either so they'll be practical, where as with bigger tires the ABS loses its mind and doesn't really function correctly so becomes more a nuisance (or so I've read.) Also, now that I realize that the ABS isn't a nanny always coming on when you're stopping on the slightest uneven surface or so forth, I know it won't hinder me off road like it has in the past. I've considered just yanking the fuse before.

So don't hate on your ABS. Get it checked. It's probably been treated badly like mine was. From the time I bought the Jeep it's been like that, so God knows how many years it's been since it was properly primed and bled.

I tell you, my world for people that know wtf they're doing! It's taken 4+ years and an OCD complex to get this single issue dealt with. What has happened to the world?

They need to create a show called "Mystery Diagnosis" except to do with cars. I always thought mechanics could figure stuff out more easily, since people actually build these things. But it seems we're just as terrible at diagnosing vehicle illness as we are human illness.

Well, that is all. I'm annoyed beyond word that my ABS is dying. At least I have properly working brakes though, and when the pump does work, it isn't kicking in several times a day like it had been since the lift. Does COG really cause that much more stopping resistance? At 2.5" of lift I'm leery to even imagine what those of you with 6" feel.

[ZJPunk98]

thanks for the post... i'll go through the process

[tank12983]

Wow greet post. I had to get a brake line replaced in the past, and they never felt great, but now I have hope as a friend of mine's farther works in a garage and has access to a scan took.

[ilive4cars0122]

That is a very interesting post. I've always wondered why our brakes suck.

[ZJPunk98]

I hope to get my hands on a tool this week. I'll let you know how it goes.

[1stblack97ZJ]

Originally Posted by ZJPunk98

I hope to get my hands on a tool this week. I'll let you know how it goes.

aight. Hopefully they are better

[9496ZJs]

I have major brake work planned for tomorrow on the 96zj. Rear calipers, rotors, pads, ebrake shoes, rubber lines and hard lines all the way to the pump.

Needless to say, a proper bleed is going to be necessary. So which scan tool would include a command to prime/bleed the pump? I have a generic brand code reader to read (you know the orange handheld they sell at AZone) and clear DTCs. But it's not Jeep specific. And I have another PC-based scan tool for my Audi. I assume these may not be adequate, no?

Is there a Jeep-specific scan tool required?

Also, any recommendations for retail store w best selection of brake line fittings that will match the Jeep original equipment? I'll be custom forming/flaring the lines, but I hope to save the OE junctions.

[ZJPunk98]

I still have not been to the steelership to find out which tool is required to bleed the brakes. I will stop tomorrow and find out. I am assuming the tool is going to be jeep specific or a tool with jeep software loaded

[Airborn]

Definetly need to know what tool to get. Or i will have to go to the stealership also. Im having the same problem. even with me going to school for auto tech. i was just thinking i needed i new master cylinder. but i am going to try this first.