AUTOMATIC CAR WASH PROBLEM

Never noticed this behavior leaving the wash. Just entering it. Never in anything but default drive modes, switching from Drive to Neutral. It rolls just fine with all 4 wheels turning if I coast in Neutral. Just entering the wash we experience this.

I haven’t checked the display to see what it is showing. Every time I have when driving around it shows the vehicle only getting power to the rear wheels. I’ve even just slammed my foot on the gas in the snow to see if it would change or if I would end up doing a doughnut…nothing. Just a minute moment of a wiggle and then forward motion. Display still never changes to my recollection. Wife’s DD though so I’m not in it much.

I do have the 2 speed transfer case, but when I look at the window sticker it calls out Quadra Trac II instead of Quadra Drive II..unlike the 2004 and 2011 Grand Cherokees we owned. This 21 we took what we could get. It also has the air suspension deleted. Which I suppose some probably see that as a great thing. I didn’t care either way. My 2011 has it and it never made me feel like it obsoleted traditional suspension. I do wish it had the Hemi like the 2011 but the V6 is peppy enough for my wife and she probably didn’t need the bigger engine anyway since she drives like a race car driver (though she says she doesn’t). She’s either 100% on the gas, or 100% on the brakes. Coasting is foreign to her! 😆. She had a Infiniti M45x premium (V8 AWD sedan) for several years. I put more brakes and rotors on that car than all other vehicles I’ve ever owned out together…

Anyway, I’ll do some more investigating. Check the display, get some video…

No problems with my 21 limited going thru a car wash .

MxRacer965 said:

Never noticed this behavior leaving the wash. Just entering it. Never in anything but default drive modes, switching from Drive to Neutral. It rolls just fine with all 4 wheels turning if I coast in Neutral. Just entering the wash we experience this.

I haven’t checked the display to see what it is showing. Every time I have when driving around it shows the vehicle only getting power to the rear wheels. I’ve even just slammed my foot on the gas in the snow to see if it would change or if I would end up doing a doughnut…nothing. Just a minute moment of a wiggle and then forward motion. Display still never changes to my recollection. Wife’s DD though so I’m not in it much.

I do have the 2 speed transfer case, but when I look at the window sticker it calls out Quadra Trac II instead of Quadra Drive II..unlike the 2004 and 2011 Grand Cherokees we owned. This 21 we took what we could get. It also has the air suspension deleted. Which I suppose some probably see that as a great thing. I didn’t care either way. My 2011 has it and it never made me feel like it obsoleted traditional suspension. I do wish it had the Hemi like the 2011 but the V6 is peppy enough for my wife and she probably didn’t need the bigger engine anyway since she drives like a race car driver (though she says she doesn’t). She’s either 100% on the gas, or 100% on the brakes. Coasting is foreign to her! 😆. She had a Infiniti M45x premium (V8 AWD sedan) for several years. I put more brakes and rotors on that car than all other vehicles I’ve ever owned out together…

Anyway, I’ll do some more investigating. Check the display, get some video…

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Some car washes have you pull onto a conveyor such that the front and rear axles are both on (all 4 wheels), while others may just grab the front wheels while the rears are still on solid ground, which may be what's making the difference here. That's all I can imagine. If that's the case at your wash (front wheels only, initially, on the conveyor), and I've heard that the center diff is is sort of locked all the time, then maybe that's what's causing it.

MxRacer965 said:

Never noticed this behavior leaving the wash. Just entering it. Never in anything but default drive modes, switching from Drive to Neutral. It rolls just fine with all 4 wheels turning if I coast in Neutral. Just entering the wash we experience this.

I haven’t checked the display to see what it is showing. Every time I have when driving around it shows the vehicle only getting power to the rear wheels. I’ve even just slammed my foot on the gas in the snow to see if it would change or if I would end up doing a doughnut…nothing. Just a minute moment of a wiggle and then forward motion. Display still never changes to my recollection. Wife’s DD though so I’m not in it much.

I do have the 2 speed transfer case, but when I look at the window sticker it calls out Quadra Trac II instead of Quadra Drive II..unlike the 2004 and 2011 Grand Cherokees we owned. This 21 we took what we could get. It also has the air suspension deleted. Which I suppose some probably see that as a great thing. I didn’t care either way. My 2011 has it and it never made me feel like it obsoleted traditional suspension. I do wish it had the Hemi like the 2011 but the V6 is peppy enough for my wife and she probably didn’t need the bigger engine anyway since she drives like a race car driver (though she says she doesn’t). She’s either 100% on the gas, or 100% on the brakes. Coasting is foreign to her! 😆. She had a Infiniti M45x premium (V8 AWD sedan) for several years. I put more brakes and rotors on that car than all other vehicles I’ve ever owned out together…

Anyway, I’ll do some more investigating. Check the display, get some video…

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I'd love to see a video if you are able to do that.

MxRacer965 said:

Any updates on this? Noticed the wife’s 21 Summit V6 has issues when pulling into the automatic wash. Ours has conveyor belts on both sides. When we put the transmission into neutral as the front tires are on the belt the vehicle “shudders” until the back are on. Thinking the back wheels aren’t turning and it’s just getting “dragged” into the wash? I intend to take video in the next day or two to confirm and then ask the dealer about it if I find this to be the case.

Side note, I have a 2011 Summit Hemi that I’ve owne since new and it does not exhibit this behavior. Which is why this is foreign to me. My Ram 1500 and Expedition also have 4 Auto modes in addition to dedicated 2WD modes, of course neither do this either.

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Thank you for reminding me to post an update on this!

I contacted Jeep a few days after posting this, and spoke with a different person in their tech support, who contacted someone in their engineering. This person informed me that there are no issues going through car washes with conveyer belts on both sides. I was told that the conveyers that have only 1 belt can be problematic. As long as the tires are spinning or stopped at the same time, it should be fine. He mentioned that it might make odd noises when you are on a single belt conveyer, where the tires on one side are parked and the other side is turning. (He went into more engineering detail, but it went right over my head) The only thing I remember him saying was "advanced transmission and drivetrain", and that it is always in the 4WD.
I have since returned to the wash and have not noticed any issues outside of when I am in the bay, where I experience the same thing on your 21 Summit. I asked one of the car wash staff to watch my rear tires to ensure they were free-wheeling, and they were. The shuddering/jerkiness is a bit of a mystery to me, but I was told that was normal.
I'm still always a bit nervous about it, but the lack of driving issues after all of the carwashes makes me feel a bit better.
*I still have an issue when exiting the wash, as the Jeep will (about 1/3 of the time) activate its automatic "parking mode", requiring me to rotate the shifter until getting back to drive. It's always a bit nerve-wracking when I get to the end, because I never know if it's going to do it or not.

FirstTimeJeepYooper said:

Thank you for reminding me to post an update on this!

I contacted Jeep a few days after posting this, and spoke with a different person in their tech support, who contacted someone in their engineering. This person informed me that there are no issues going through car washes with conveyer belts on both sides. I was told that the conveyers that have only 1 belt can be problematic. As long as the tires are spinning or stopped at the same time, it should be fine. He mentioned that it might make odd noises when you are on a single belt conveyer, where the tires on one side are parked and the other side is turning. (He went into more engineering detail, but it went right over my head) The only thing I remember him saying was "advanced transmission and drivetrain", and that it is always in the 4WD.
I have since returned to the wash and have not noticed any issues outside of when I am in the bay, where I experience the same thing on your 21 Summit. I asked one of the car wash staff to watch my rear tires to ensure they were free-wheeling, and they were. The shuddering/jerkiness is a bit of a mystery to me, but I was told that was normal.
I'm still always a bit nervous about it, but the lack of driving issues after all of the carwashes makes me feel a bit better.
*I still have an issue when exiting the wash, as the Jeep will (about 1/3 of the time) activate its automatic "parking mode", requiring me to rotate the shifter until getting back to drive. It's always a bit nerve-wracking when I get to the end, because I never know if it's going to do it or not.

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Thank you very much for tracking down this information and posting.

@FirstTimeJeepYooper Are you saying the vehicle, when in neutral while exiting, places itself into park all by itself? Does it by chance set the brakes and beep warning of a collision too?

eleceng1979 said:

@FirstTimeJeepYooper Are you saying the vehicle, when in neutral while exiting, places itself into park all by itself? Does it by chance set the brakes and beep warning of a collision too?

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While I’ve had it put itself into park, I have never had any collision lights or beeps occur. (The first few times I went, the automatic tailgate opened while the underbody wash was going. Then it started saying that the feature was disabled. Then, I discovered that I could turn off the hands-free lift gate feature. No problems on that since.)

You might want to have it checked out. Early on, mine it would slam the brakes on and place itself in park sometimes without a collision warning. It clearly had wiring/harness issues and I no longer own it. It could happen while driving, as another user had happen in the middle of an interstate at speed for no reason.

Been a while since I posted on this. It has taken this long for schedules, timing, etc to work such that my wife could drive in while I took video. It *feels* like the rear wheels are being dragged when inside the car but obviously they are rolling. Interesting that the rear tires spun in reverse when they hit slick cement. No issues pulling out.

Thoughts??? It was in neutral. Both sides of the car are on a moving conveyor. Only an issue when pulling in.

Entering Wash

MxRacer965 said:

Been a while since I posted on this. It has taken this long for schedules, timing, etc to work such that my wife could drive in while I took video. It *feels* like the rear wheels are being dragged when inside the car but obviously they are rolling. Interesting that the rear tires spun in reverse when they hit slick cement. No issues pulling out.

Thoughts??? It was in neutral. Both sides of the car are on a moving conveyor. Only an issue when pulling in.

Entering Wash

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As Sarge and others mentioned, front and rear are always tied together. Neutral disconnects from engine, but not front/back. Front wheels hit belt and stop rolling, back wheels keep rolling causing wind up in drivetrain. Rear hits gap getting on treadmill and unwinds the built up tension. I had never seen a car wash like that.

Obiton said:

As Sarge and others mentioned, front and rear are always tied together. Neutral disconnects from engine, but not front/back. Front wheels hit belt and stop rolling, back wheels keep rolling causing wind up in drivetrain. Rear hits gap getting on treadmill and unwinds the built up tension. I had never seen a car wash like that.

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I have never had that issue with any other vehicle though. I have a 2011 GC Summit as well that doesn’t exhibit this behavior…wife had a Infiniti M45x (AWD) that also did not do this (not that those have the same drivetrain).

I have a 19 Ram 1500 and a 19 Expedition Max that I generally have in 2WD so those aren’t a great comparison.

Other vehicles use a viscous coupler at the input/pinion shaft on the rear differential to allow the rear slip/disconnect. This is typical in AWD vehicles with a primary FWD with RWD assist. E.g. dodge Journey, pretty much every Toyota car/rav4 that is AWD. I would assume your Infiniti is this way. Any vehicle with a transaxle must use a viscous coupler at the rear to allow for turning/slippage. Only when a transfer case is used, this requirement is removed.

Jeep is RWD primary with FWD assist but in full time AWD only using the transfer case electronic clutch (depending on trim/transfer case type), which for all purposes is locked fully and commanded to slip in order to split the torque from front to rear via computer. The only way the front can be unlocked from rear is by following the transfer case neutral unlocking, which is not related at all to the gear selection knob. The comment of one rear tire rotating backwards, while vehicle is traveling forward, is classic open rear differential behavior as the wheel with the least amount of traction will rotate backwards while the other is forward due to to differential being open (elsd disengaged) and the center spider gears causing the reverse rotation. If you would raise the rear off the ground and turn one wheel by hand, you will notice this behavior. The rear elsd is normally open and commanded to lock when required/commanded, so rear is open differential all the time, hence the car wash problems.

Quadra Trac 2 applies the brakes to wheel with least traction in order to allow power to be transmitted to wheel with most traction. It is brake based using traction control.

Quadra Drive 2 uses electronic clutches in front/rear to send power to wheel with least traction. This is why Jeep deleting elsd is a big no-no in higher trims with this transfer case. It renders the system useless for left to right torque split. I suspect they deployed QT2 software using braking to overcome this which is crooked as hell due to paying for the QD2 feature set yet the elsd being removed.

Both have a electronic clutch in the transfer case. Due to your current vehicle being QT2, I suspect it is applying brakes and locking one rear which would cause the opposite to reverse rotate due to open rear differential, and fronts stationary. Something, somewhere must slip if front is stationary and rears are moving. In QD2, I suspect it is slipping in transfer case.

Obiton said:

As Sarge and others mentioned, front and rear are always tied together. Neutral disconnects from engine, but not front/back. Front wheels hit belt and stop rolling, back wheels keep rolling causing wind up in drivetrain. Rear hits gap getting on treadmill and unwinds the built up tension. I had never seen a car wash like that.

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This needs some clarification: they are ‘sort of’ always tied together, but not really; The front axle, as I’ve come to understand, is automatically disengaged by the center diff, leaving the car to ostensibly operate as RWD unless the computer decides to engage the front axle.

I haven’t found any white papers or any other reliable info about what the parameters are, but one would think when the car is in neutral in auto terrain mode the center diff would leave the center diff disengaged.

However, maybe if it detects some wheels turning,, and others not (ie one wheel stationary on a conveyor) it then engages the front axle even in neutral.

The only other thing that could possibly cause drag would be if you have a V8 and you have the brake hold feature engaged, as far as I can imagine.

Sarge said:

This needs some clarification: they are ‘sort of’ always tied together, but not really; The front axle, as I’ve come to understand, is automatically disengaged by the center diff, leaving the car to ostensibly operate as RWD unless the computer decides to engage the front axle.

I haven’t found any white papers or any other reliable info about what the parameters are, but one would think when the car is in neutral in auto terrain mode the center diff would leave the center diff disengaged.

However, maybe if it detects some wheels turning,, and others not (ie one wheel stationary on a conveyor) it then engages the front axle even in neutral.

The only other thing that could possibly cause drag would be if you have a V8 and you have the brake hold feature engaged, as far as I can imagine.

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Everything I have been able to find points to the center differential being engaged but not locked by default. I can’t confirm, but I believe the Front Axle Disconnect (FAD) is part of the front differential, not the Transfer case. The FAD is only disconnected at highway speed. In the car wash scenario, the center differential would provide resistance to the rear wheels turning but still allow slippage for the Jeep to be pulled onto the treadmill while storing some bind energy. When the rear wheel hits the gap and breaks traction, it spins backwards due to the rear differential as expected. I don’t know if there is a technical reason not to loosen up the clutches on the center differential or disconnect the FAD when in neutral.

Obiton said:

Everything I have been able to find points to the center differential being engaged but not locked by default. I can’t confirm, but I believe the Front Axle Disconnect (FAD) is part of the front differential, not the Transfer case. The FAD is only disconnected at highway speed. In the car wash scenario, the center differential would provide resistance to the rear wheels turning but still allow slippage for the Jeep to be pulled onto the treadmill while storing some bind energy. When the rear wheel hits the gap and breaks traction, it spins backwards due to the rear differential as expected. I don’t know if there is a technical reason not to loosen up the clutches on the center differential or disconnect the FAD when in neutral.

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I wouldn't say the FAD is only disconnected at highway speeds. Mine disconnects all the time when in just driving around town 0-25mph. It doesn't really have much to do with speed more about your driving style and acceleration.

SweetAndLow said:

I wouldn't say the FAD is only disconnected at highway speeds. Mine disconnects all the time when in just driving around town 0-25mph. It doesn't really have much to do with speed more about your driving style and acceleration.

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I knew I should’ve just said “at speed”. Just trying to make the point, that the default FAD mode is engaged and the center differential is also always engaged. I have not studied it the disconnect. My daily driver is an 09 JKU. Wife drives our WL during the week. Then when I do drive, she tends to fuss if I’m fiddling with the toys instead of watching the road.

How about everyone ask the guy who flat towed a WL without unlocking the transfer case what the default behavior with power off is?

Elsd diff video
Eaton ELSD

Transfer Case Teardown and tech
NV245 Breakdown

NV245 is old as dirt. It is used in WL. Read here
WL Quadra What?

There is an "open" 4HI, a limited slip transition to "locked" 4HI via clutch pack, neutral, and then an "open" 4LO, then a “locked” 4LO via clutch pack. Key note, it is always 4x4 unless unlocked.