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Unread 02-09-2015, 09:54 PM   #1
Jurassic_Jeep
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Join Date: Nov 2014
Location: Edmonton, Alberta
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2014 GC Summit V6 - thud/jerk explained?

hello, new member here. Had an eureka moment and thought I share for some feedback.

Some background, I have a 2014 GC Summit with the V6 and it has 4000 km on it. I LOVE THIS JEEP!! I live in central Alberta and its freezing here its –25 oC in the morning. Snow and ice every where. Last couple of weeks, I started feeling this ‘thud’ when I press the accelerator after rolling stops. Nothing to uncomfortable but still, you can feel it. I read this thread and got all paranoid that I have lemon. But then I noticed a pattern in the 4 or 5 times I’ve felt this. Noticed it only happened when I had the wheels turned to make a turn. I’ve been watching the trans temp and that little gear number like a hawk recently and because of the winter, it rarely goes past 60oC from the cold. Most of the time I could be driving 15 km into my trip and the temperature is still at 45oC and guess its running relatively cold. Today I did test. While in Auto Terrain and wheels straight on a snowy but also icy road, I pressed the gas lightly and then stopped before it would shift in to second. No thuds, perfectly smooth. I did this just to make it was in first gear (somebody reported here that even though it said first, on the gear changer thing, it still felt like it was in second). I turned the front wheels, and again, did the same thing, again perfectly smooth acceleration. Then, I pressed the gas a bit harder (not floor it, just enough to loose some traction), small thud with a jerk as if it got traction on spinning wheels (again I'm still in 1 gear speed now, <8 km/h). This to me sounds like, the computer is switching between auto to snow mode (or sand whatever it thinks) and once it gives power/traction to wheels with grip it gives a jolts. Now when I put the terrain in snow mode and hit the gas (it starts of in second in snow mode), there is no noticeable thud.

So, im thinking this thud might be the slack in the 4x4 system/transfer case or delay in the computer to react to the spinning tires. I don’t think its coming from the 8 speed but wanted to know what you all think.

thanks and sincerely,


Last edited by Jurassic_Jeep; 02-09-2015 at 09:56 PM.. Reason: more accurate description
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Unread 02-12-2015, 06:17 AM   #2
2kg4u
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Sounds like the nannies kicking in to stop wheel spin.
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Unread 02-15-2015, 12:37 PM   #3
Jurassic_Jeep
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thanks, 2kg4u. Its close to that.

After doing some more research, I found a TSB for it. It is the software for the 4WD (e-diff i think). This is exactly what I'm experiencing:

http://www.wk2jeeps.com/tsb/tsb_wk2_2102114.pdf

Not that urgent so just going to bring it up on my next oil change.
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Unread 02-15-2015, 01:45 PM   #4
ColdCase
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You have a V6, none of which come equipped with the ELSD that TSB applies to. You'll have to find another TSB or service bulletin.

The system does not switch between modes, the mode switch selects a traction strategy the traction computer uses. There could be a slight thud felt when the traction control computer engages the clutch packs in the transfer case, and you could also feel/hear an ABS type sound as the BTC starts to work. In snow mode, the packs are usually engaged from the start... so you shouldn't feel a thud unless there is a lot of driveline play somewhere else. The clutch packs could be released on a rolling stop, but then are applied when you touch the accelerator which is the thud you feel, I dunno.

Then there could be a bit of miss adjustment in the transmission.

Then Jeeps are not known for the smoothest of operation, functional and effective, but often not so smooth. Its a truck after all
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Unread 02-15-2015, 02:41 PM   #5
Jurassic_Jeep
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Thanks ColdCase for clearing this up. I don't mind if this is a truck thing its just that driving this Jeep is so smooth, the one time something is off you'll know, no matter how minor.

The TSB I listed refers to another TSB for the V6 and it groups this issue under 'transfer case enhancements'.
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