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Discussion Starter #1
Hey all, have been discussing this on an Australian forum and discovered I was not alone.

The vehicle, stock JK 2010 (at the time) six speed manual.

The situation, attempting to climb muddy, slippery slope.

The problem.......

After getting 3/4 of the way up the hill with some heavy right foot action in 4LO (so ESP is disabled as much as it can be) second gear (all 4 wheels spinning) no further progress was possible so slammed the brakes on, only to find the pedal rock hard. Both feet were not able to move it! Several seconds later after uncontrollably rolling backward down the hill with no brakes the pedal released and normal braking returned.

I have written to both Chrylser Australia and Chrysler US, both just said take it to a dealer. I have already discussed the problem with the dealer and all they said was they could find nothing wrong.

I dont believe there is anything wrong as such, it would seem more like a design issue in the ABS / Traction Control system, or maybe an issue with low vacuum after sustained high rpms??

There was a recall a few years ago for 2007 models that did something similar, except after going up a hill (but not encountering wheel spin) the pedal went to the floor with no brakes and came good after pumping a few times. This has been rectified.

So far I have discovered about 8 vehicles down here ranging from 2008 to 2010 that have suffered the same problem under the same conditions and I am wondering if anyone out there has found the same thing.
 

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The Bad Guy
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The only thought that comes to mind is that it could have something to do with the BLD, especially since you said, "all 4 wheels spinning."
 

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Discussion Starter #3
Yes, my thoughts exactly.

Low vacuum pressure has been suggested as well, but I know if I pump the brakes a few times with the engine off I can still hold the vehicle with one foot. This was no pedal movement at all with both feet!

Just cant get anyone to take me seriously at the moment, hence why I am looking to see if anyone else has had the same issue.
 

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The Bad Guy
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Obviously the dealer won't be able to duplicate it. Perhaps you could have a passenger video tape it, along with another person taking video of the exterior conditions, then edit the video together.
 

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Could there have been dirt/mud on the caliper, rotor and on the pads? That's not going to let you brake.

When's the last time you checked the rotors, pads, lines and flushed the fluid? I'd inspect the calipers too to make sure that the piston's aren't gummed up.
 

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MARGARET, 10-14-51\6-1-12
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let me chime in here, its really not your "brakes" its your ABS.... let me explain.

imagine your driving your jeep across a frozen lake at say 35MPH . then i want you to mash the brakes on hard, what happens,,, nothing really because the abs is fighting wheel slippage because the abs does not want the wheel to lock so the little abs motors " pump if you will" at a rate so freaking fast that it causes a hard brake peddle .. like not having brakes at all. and you do not regain a normal peddle until the wheels slow enough. mud and wet grass will do the same thing... if you dont believe me,,, next time you wheel in the mud just pull your abs fuse,,,,, and this is the main reason i did this mod. http://www.wranglerforum.com/f33/abs-esp-bas-off-mod-with-pictures-87119.html

ps, i drive on a frozen lake at my parents house at least 10x every winter, been doing this for 15 plus years,,, this is how i found out about the issue your having.

and please remember this is just my opinion and i should not be flamed for the above statements, it is completely true to the best of my knowledge
 

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The Bad Guy
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That is a good possibilty. OP, did you notice any vibration in the brake pedal or any sound when this happened?
 

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I'm not particularly educated on this stuff, but I'll toss it out there as something that could've been a factor--how about the anti-stall feature?

You were in 4Lo with a manual trans. I know the computer invokes RPMs to avoid a stall, but would it potentially prevent braking too? Did you happen to try to shift into neutral? (Admittedly not a terribly good idea if the problem is rolling backward . . . .)
 

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The Bad Guy
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Mike, the brakes definitely work with the anti-stall. The engine actually fights against the braking. In the OP's case he was spinning the wheels when he attemptrd to brake.
 

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Vin said:
In 4 wheel low, the ESP is automatically turned off. Will the ABS still be active?
Good question. I'm wondering too
 

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I AM THERE4 I JEEP
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Interesting thread. I haven't experienced this or heard of it but I'm thinking the answers to why this happened have been mentioned in previous replies. OP, have you had this happen since or under normal driving conditions?
 

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I have had it happen. And it is usually during the wheel spin and angle of approach/departure that create it. I feel it is as stated. ABS is trying to apply it's rules of engagement based on wheel spin. And thus, the brake pedal is hard.


Bob K.
 

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I AM THERE4 I JEEP
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Another thing I've noticed is that if your sitting on an incline in traffic under normal conditions and you release the brake, the JKs will hold that position for a few seconds to prevent roll back. If you've ever tried to re-apply the brake while it is holding you still, you'll notice that the brake is hard and very resistant to being depressed during this moment.
 

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Discussion Starter #19
ESP - na, the Hill Start Assist was disabled within the first week I had the JK - drove me nuts!

Could there have been dirt/mud on the caliper, rotor and on the pads? That's not going to let you brake.

When's the last time you checked the rotors, pads, lines and flushed the fluid? I'd inspect the calipers too to make sure that the piston's aren't gummed up.
Hey goofy, my JK was only about 4 months old at the time, The first time it happened, I was screaming up this hill to try and make it to the top, with a Nissan Patrol (on great big mud tyres) waiting at the top to pull us up the rest of the way.

A 2009 JK went up first and upon getting as far as he could stabbed the clutch and brakes only to find the pedal hard and started rolling backwards. Fortunately the hill was heavily rutted so it was like rolling back on rails.

After this happened we went right over it checking for ABS cables broken, brake lines pinched, wheels and calipers full of mud etc.. We found nothing.

So the second JK went up (mine, 2010 model) but at least being aware that something may go funny! Same deal, 3/4 of the way up ran out of forward momentum, stabbed the brakes and clutch together and clutch pedal felt like it had been welded in place. Dropped to neutral and put both feet on the pedal using the steering wheel as leverage and still could not move the pedal.

A few seconds and 10 to 20 metres later the pedal moves and the JK slows to a stop.

Next another 2009 model heads up, exactly the same result.

I have only had it happen once since, but then have only once been on the same situation trying like mad to get up a long hill and having to give up.

I got another email back this morning from Chrysler Australia's customer relations person and I can tell you she is not doing much for customer relationships at the moment!

From: David Baker
Sent: Thursday, 1 December 2011 10:47 PM
To: Alisha Giltinan
Subject: RE: JK Wrangler Brake issue

Thankyou for the reply Alisha.

I have mentioned it to the Dealer in the past, and they, as you, were unaware of any issues nor could they find any faults in the system. Personally I do not believe it is a fault in the system as after discussions on an Australian Jeep forum over the last 2 days, I am already aware of 8 other vehicles across Australia that have experienced the same loss of brakes under the same situation and ended up rolling uncontrollably back down a hill.

I have already raised the issue with Jeep US when I could not find a contact for Jeep Australia but they had the same response you did – not heard of it before and suggested I contact a Dealer.

My concern is someone is going to get into the same situation and roll uncontrollably into serious damage, injuries or worse.

I believe this needs to be looked into further, but I do not know who to talk to or where to go from here.

Cheers, Dave.

David Baker
_______________________________________

Hi David,

Chrysler is happy to assist dealerships where possible to rectify concerns, however if they can not fault the vehicle they cant fix anything.

We are happy to ensure the dealership check over and ensure vehicle is safe etc however this requires you attending a Chrysler Jeep Dodge retailer.


Kind Regards


Alisha Giltinan
Customer Relations Executive
Chrysler Australia Pty Ltd
So I guess what I am saying is guys please be aware of this "undocumented feature" as I do not believe I am going to get anywhere with Chrysler. When someone is killed from rolling backward uncontrollably there will be no one to around to mention they had no brakes so it will be blamed on driver error.
 

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Discussion Starter #20
An update to this one: Still no response from Chrysler, I guess they are trying to keep it quiet would be my best guess.

Though now interestingly the 2012 models have this new "Air Pump" behind the front bumper. This new air pump is actually a vacuum pump, designed provide extra braking assistance when required "which most people will never use", ie, if the resevoir runs out of vacuum and the pedal would become rock hard this will kick in and create some more vacuum so you have brakes again.

Annoys the crap out of me that Chrysler Jeep say they have no idea what I am talking about whilst at the same time already installing a fix for the same problem into the new model.

They obviously already new about it long before I asked about it and are simply stalling as long as they can before being forced into an international recall of ALL 2007 to 2011 JK Wranglers - though I could understand wanting to hold that off as long as possible, but how long? Until someone is killed?
 
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