jeep58

Yes will do Thanks!

jeep58

I think I found the problem, Positive battery that is on there is not a molded cable, kids hooked up a stereo and spliced cables onto positive terminal ones that used for marine applications. I disconnected the positive cable and found it to be all rusted were cables get bolted on to connector, cleaned it all up with wire brush. Started up jeep and all gauges are running in normal range no check gauge light lit up. I also went to the number two pin and checked voltage I now have a reading of . 99 -.130 volts and fluctuating before same pin I was getting up 3.35 volts. Before cleaning the connection check gauge light would come on and off power windows would not operate and the a/c would not turn on. Keeping my fingers crossed That this was the problem, I will let you now the outcome and I want to say Thank you for you precise trouble shooting !!!!!!

Noah911

Dang! That was along the same lines of the other thing I was going to say... I felt that you finding the voltage reading from off pin #2 PCI Bus was going to be the easy first step in troublshooting, and should be obtained first since it provides sound data. I started to type up my second thought in the begining of my reply (it went something like - I think it could possibly be one of two things...). My thoughts were on it being related to either the PCI Bus system, or it could be due to the way in which the factory has the main power and ground wires all loomed tightly together in that sleeve wrapped in electrical tape. With the extreme temperature fluctuations going on in the engine compartment, degradation and insulation issues, and those wires being kept like that crossed all in one sleeve has the potential to create problems - arcing ect... If finding a module or two being corrupt via the PCI Bus testing procedure, the next thing to consider would be what causes them to become corrupted. Those wires the way they are has the potential to do just that. They can even fry your alternator being the way they are, or some computer modules.

It wasn't the exact same as what you have going on, but would have pointed you directly to it, to see it... People always say to go straight to the battery and its terminals first, when experiencing many different kinds of problems, especially electrical ones. Then grounds, etc

Thank you for the update. I know you are probably glad to have found the likely cause of your troubles! Judging by the most recent readings, it looks like your PCI Bus system is happy again! Hopefully, you are in the clear..

jeep58

Ok so the break line rusted out "front to rear" someone already replaced a section of the line. I took out the rusted section section and replaced it. I bleed the brakes and now the right front brake is lock up, thinking it is a bad caliber I replaced the caliper with a new one and changed the front pads. Problem now is the right front side is locked up cannot turn the tire. I have no idea what is going on? Please help with this one , Thanks

dave1123

Open the caliper bleeder screw and bleed off the pressure. If the wheel turns then, my guess is the brake hose has collapsed internally and is acting like a one way valve and not allowing the pressure to bleed back to the master cylinder.The WJs are really touchy about letting the calipers hang on the hoses. If that's the case, you're going to have to replace the brake hoses. At least that one side, but I'd do both to be safe.

jeep58

I open bleed screw and fluid runs out, I disconnect brake line and fluid run out, Caliper will not go back out by itself.

jeep58

I took out brake hose and then was able to push back on caliper, going to get new hose and see if that works!

Noah911

I can help with ideas for things that could possibly cause brake drag to occur.

It is not very likely, but it is still possible for a new, or remanufactured caliper to be defective. It is something to consider.

The small hose connected to the caliper could be degraded internally as was mentioned already, and turn into a one-way valve preventing the caliper from releasing. It sounds like you looked into this, and you are seeing fluid being released as is normal when you opened the bleeder. I had a thought it was possible for rust to have been introduced somewhere, and was blocking off this passageway? That doesn't seem as likely since you have a good stream of fluid coming from the bleeder when you open it. If the flex brake line attached to the caliper is collapsing on you, and is acting as a one-way valve, I would think it should still slowly release to allow the caliper piston to retract over time right? These flex lines are really important though either way, and it wouldn't hurt to replace them if they are getting old. Especially, since you are having this problem. If you don't find any other reasons.. Then, you know it could essentially be ruled out.

Calipers can bind on corroded bushings, or slide surfaces. I imagine you have coated the sliding area of both the caliper, slide pin, and pads with an aluminum lubricant like never cease? I think this is still worth mentioning though.

A loose worn wheel bearing is a possibility.

Loose caliper mounting.. having mis-assembled components is a possibility.

A brake booster with a maladjusted brake booster rod has the capability.. If it is too far extended, it could cause the master cylinder to think you were applying the brakes. The brake booster rod is a possibility. You have not touched the brake booster though, and it should not become maladjusted on its own like that. If when someone is replacing the brake booster, it could come fully extended that way when bought new. This would potentially be able to cause the application of the brake(s). I am not to well versed on it, and I am not not fully sure that a brake booster rod out of adjustment would be able to effect just the one wheel/caliper, could it?

One more idea.. This is specific to the Grand Cherokee of the years I think 1999 - early 2000's. look for grooves worn in the rails on your steering knuckles. The rails are the things that the bottom of your pads metal backing plates rest on. If the rails are grooved, or there are notches on the slide surface, it will prevent the pads from sliding in and out. I imagine it is possible for this to cause what you are experiencing.

jeep58

I put the wheel on the jeep and it turns both sides, The brake light still comes on dash board and after sitting overnight gauges go back to not working disconnect and reconnect battery and the gauges will work again except for the brake light that keeps coming back on. I put a new section of brake line in changed front pads ( were worn) and changed front right caliper it did not release as good as the driver side when I changed out the pads, Why does brake light keep coming on?

Noah911

Both the parking brake light switch and the brake proportioning valve switch complete the brake light circuit by providing a ground when set.

The sensor is on the proportioning valve right next to the master cylinder. It is just a on/off switch connected to ground. The sensor detects the pressure being sent between the front and rear braking systems. There is a redundancy to the braking by dividing it into seperate front and rear systems. If the front goes out you will still have working rear brakes and vice-versa. If pads rotors drums etc are worn the pressure for that system will not be correct, and give you the brake warning light.

As a test.. Unplug the sensor at the proportioning valve. If the brake warning light does not go away after you unplug it, then the parking brake switch is the reason for the light. The switch is either sticking in the on position, or it is shorted to ground somewhere along the parking brake switch wiring pathway. However, if unplugging the proportioning valve sensor results in the brake warning light turning off, then it is the proportioning valve sensor complaining.. that is the reason for the brake warning light being on.

You can remove the switch and check if the switch is now open. If it is, the prop valve spool valve is moved to either the front or rear.

What may have happened in your case was you opened one side of the system to bleed it, and during the course of doing so, you caused the pressure imbalance "spool" to move to trigger the warning light. The "spool" is not self-resetting once the pressure balance is restored. You must bleed the other side of the system to get the "spool" back to center, thereby turning off the warning light.

If the light switch was triggered by pressure difference between the front and rear brakes, you can reset it if you push on the brakes pedal hard for ten seconds or so with the car in park, engine running; that is supposedly one way to try to reset the switch.

jeep58

Once again thank you the detailed answer, I will check!

jeep58

I disconnected the brake proportioning switch at the master cylinder, light still on also disconnected switch for the parking brake still on. Is it possible that the ecu brain computer is messed up again, when I started the jeep it started then died I then restarted it and it worked , the computer that is in it is a rebuilt computer I brought online about two years ago.

dave1123

On the WJ only 2 things turn on the brake light in the dash. Setting the parking brake or low fluid in the master cylinder.

jeep58

Ok so parking brake is not on and master cylinder is full.

dave1123

There is one other scenario listed in the FSM. If the ABS light bulb is burnt out, the "brake" light will illuminate. I had that happen when I took the bulb out. It's possible the ABS system is involved with your problem. IDK.