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Soft brake pedal on my Gladiator Rubicon

jc99

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Some more info about the brakes on the 2021 JT Rubicon Diesel..... If you have the adaptive cruise control (ACC) give this a test and see what you find. I'd be interested to see what others find.

-set your adaptive cruise control
-well far away from a vehicle Increase the ACC speed so you start to quickly climb in speed
-As you come close to a vehicle in front the ACC will start to brake
-'Carefully' apply your brakes with the pedal, you should find that the pedal is solid and will work very well which is much different then normal. This is due to the ACC already applying the brakes

I say be careful as I found this out when the ACC wasn't braking as fast as I would like and I pressed the brakes hard and went into lockup/ABS immediately on the highway. What I learned from this was you need to be very careful how hard you apply the brakes when ACC is braking, or you need to tap the brakes first to disengage the ACC/ACC braking then the brakes will work a normal (ie mushy).

I feel like there is something wrong with respect to the ACC actuator either air in it or when the brakes are pressed fluid flexes back into the ACC system as well as presses the brakes. I however don't know how in detail the system works. The developer at Jscan (OBD app) told me the JT doesn't have the same type of actuation as the JL so he hasn't added the ABS bleeding procedure as it isn't necessary.

As I stated in the previous post I did do a full system fluid replacement/bleed and cycled the ABS by skidding on gravel to try and make it actuate (not sure if that's really works or not). I felt after the fluid replacement the brakes were a little bit better but still much mushier then I expect/want.
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Toyfrog

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2021 Mojave and I have the same issue. Buddies 2020 Rubicon with Mopar lift and 35’s feels way better than mine. It will be going to the dealership soon.
 

Green_Gladiator

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Digging up this older post from a search. I’m experiencing all of the above symptoms on my 21 Mojave. (Gas) If I hit the brakes it feels mushy but if I give them a pump they feel nice and hard. (that’s what she said). Tonight I was at a drive thru and I got the pedal to fade all the way to the floor, but in one pump it was fine. It stops fine, but doesn’t feel like it should. I do, however, remember my JK being this way. I figured it would be better on a new vehicle. I guess not. Anyone get info from a dealer or mechanic?
Hey bud! I have the same issue w/ my gas Mojave ... Curious if you've have it adressed or still experiencing it?
 

azmojave

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Hey bud! I have the same issue w/ my gas Mojave ... Curious if you've have it adressed or still experiencing it?
Living with it and accepting it as “normal”
 

Toyfrog

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Hey bud! I have the same issue w/ my gas Mojave ... Curious if you've have it adressed or still experiencing it?
Do you know when the trucks with issues were built? My 21 Mojave was built mid January of 2021. My buddies 2020 Rubi doesn’t have the mushy breaks like mine does, just wondering if it may be a brake booster issue from factory?
 

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jc99

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Do you know when the trucks with issues were built? My 21 Mojave was built mid January of 2021. My buddies 2020 Rubi doesn’t have the mushy breaks like mine does, just wondering if it may be a brake booster issue from factory?
Any chance you can check the brake booster and master cylinder part number on your buddies that doesn't have the mushy brake pedal?
 

Toyfrog

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Any chance you can check the brake booster and master cylinder part number on your buddies that doesn't have the mushy brake pedal?
I will call him in the morning and see if he can swing by the house and check it out. Damn good idea. 👊🏻
 

ShadowsPapa

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My brakes feel and work fine regardless of ACC mode - braking, not braking, whatever. That tells me some folks are having a problem..........??
 

Green_Gladiator

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Do you know when the trucks with issues were built? My 21 Mojave was built mid January of 2021. My buddies 2020 Rubi doesn’t have the mushy breaks like mine does, just wondering if it may be a brake booster issue from factory?
Not sure of others .. my build was 3/1/21 ...
 

CreepyJeepy

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Diesel here. 21

While the pedal isn’t as hard as my Miata with brembos, stainless, and dot 5.1 they do not fade (and I tow my trailer a lot) and stop as expected. There is also no pedal softness that occurs when auto start is engaged.
 

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CLM

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Hi, I wanted to give a brief update, I had started this post last July. Sometime last year I spoke to someone at the local dealer, they reminded me that the diesel has no engine vacuum so it's an electric or electronic brake booster. So there's that. He said people complain about them all the time, there's no specific fix, and just live with it. So actually, the brake pedal feel is much better now than it was almost a year ago. I have no idea why that is, but it's fine now and feels like any other truck.
 

J3colt

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Not sure of others .. my build was 3/1/21 ...
My JT Rubicon (gas) just passed 1100 miles and I noticed a change in the brake pedal feel as described here. Mine was built 4-2021.

Today was 80 degrees, and I was running the A/C a lot on the highway for the 1st time since buying it. It seems much different and the pedal practically goes to the floor before it stops.
 

ckgjt

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I have the same issue on my 2020. many times the pedal feels like there is a swollen line or some other internal leak as there is no fluid loss. one pump and all is good. I am going to switch to steel braided brake lines and hope that fixes it..if not I will live with it
 

jnack

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I have the same issue on my 2020. many times the pedal feels like there is a swollen line or some other internal leak as there is no fluid loss. one pump and all is good. I am going to switch to steel braided brake lines and hope that fixes it..if not I will live with it
curious if you did this and if any improvement? i have steel braided in rear but not front
 

ckgjt

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curious if you did this and if any improvement? i have steel braided in rear but not front
havent changed them out yet..I unfortunately had a major heart attack and triple bypass not too long after i posted and just recently started driving..still going to be awhile before I can pull my sorry ass up into my Jeep :(
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