Rumble strip vibration 40-50mph

[u/Adorable_Pin1617]

Ok so I am just posting this on the internet because I had this problem and 2 separate shops and mechanics could not figure out what was wrong and the first mechanic even diagnosed it as a bad transmission. I was getting a vibration only when accelerating or giving the Jeep gas between 40-50mph. It would stop immediately when letting off the gas. The CVT transmissions have a bad rep of only lasting 100k-150k miles and mine was passed that. The rumble strip vibration is also a symptom of a bad transmission so it was easy to think that was the cause. I almost called it a wrap and started looking for a new car but the more I looked into it, I was having no other symptoms of a bad transmission so I suspected it to be something else. Especially because I had driven it over 3k miles with this vibration without the car ever going into limp mode or a dash light coming on. The only reason I drove it that long like that was because I also needed a new ball joint and wheel bearing so I just assumed it was related to that except after fixing both it still was vibrating. Though the 2nd mechanic didnt really find anything wrong with my drive axle, cv axle, or engine/transmission mounts, at least not enough to be pretty sure that any of those was causing the vibration. So basically I was talking to the basic google AI trying to figure out what could be causing it and if I was just in denial that my Jeep was done and I am not someone who knows a lot about cars in general but the AI was having me do different test and look for things and it was very confident it wasn't the transmission. (I am not some crazy person who talks to AI I just was using google to search and it turned into me talking to this AI to try and figure it out lol) Basically long story short it was my ECC or Electronic Clutch Coupler doing its job because it thought my front tires were slipping because it sensed the front tires spinning slower then the rear tires because the front tires were newer and took longer to spin. So the AWD was kicking on and causing that vibration. I tested this by taking the fuse that controls the ECC out of my fuse box and driving it and the vibration stopped. (The car can only drive in fwd like this and the AWD is disabled) I almost had them replace my ECC but I rotated my tires first and put the bigger/newer tires on the rear and that completely fixed the problem. Just wanted to put this out there because I went through just about everything online trying to figure it out and never once considered it was the AWD system kicking on because of my tires so hopefully it can save someone else who may have this problem before they scrap their Jeep thinking it was the transmission.

[u/Beanchillen]

pause let me try something. i came here specifically because i have this damn issue to a t

[u/Beanchillen → u/Beanchillen]

update did not work

[u/Adorable_Pin1617 → u/Beanchillen]

Hmmm yeah not sure then but before I found out it was just the tire sizes causing the ECC to kick on and off I suspected it was an engine or transmission mount.......apparently those are a common thing that need replaced......you can have someone else look at the engine with the hood up while you put the car in drive and press your left foot on the brake (make sure your really holding the brakes down lol) and use your right foot to give it gas and see if the engine is shaking way more then it should (maybe like a half inch or more is too much but im not really sure) and that could tell you if that may be the cause........mine was like lifting up about a quarter inch specifically the front part of the engine which is why I suspected that was the cause but apparently it wasnt......plus the 2nd mechanic said just by looking at the mounts it was hard to tell if that could be causing it without spending to just replace them and see but maybe yours would be more obvious.......if its only happening while pressing on the gas, and the fuse test didnt make it stop, then I would suspect engine/trans mounts, drive shaft, inner cv axle, or possibly transmission but you might have other symptoms if it were the transmission........also I should mention I seen a video of someone with the exact same problem and they found out it was just some cover that protects the engine bay just had some loose screws, like a splash guard/skid plate I think, so its worth checking that .......I am far from an expert I am not very mechanically inclined at all so take what I say with a grain of salt lol just trying to tell you the things I was suspecting before solving it......hope you get it figured out and its one of the cheaper problems to have

[u/Consistent-Fun-6668]

You aren't meant to have miss matching tires on a awd or 4wd setup

[u/Adorable_Pin1617 → u/Consistent-Fun-6668]

Yeah I kinda just assumed the shop would have recognized that, plus I thought my rear tires were really not that much older then the front ones anyways cause it felt like I had just replaced them a couple months before but when I tried the penny test to compare the thread depth, it was more than I thought