PDA

View Full Version : Rough upshift/lockup after towing?



KW58
10-11-2018, 02:43 PM
Howdy everyone! First post here for me, I did a fair amount of searching here and on Swedespeed but couldn't find anyone else with the same issue, so I'm guessing it's not a common one.

2014 XC60 T6, just towed a trailer for the first time (probably a 1500lb trailer, drove about 500 miles with it, almost all highway). The car drove like a champ, no issues while towing. However after unloading the trailer, it now has a pronounced shudder (shakes the whole car) when the transmission locks up after upshift. Shudder is worst in 3rd / 4th gear, especially when going uphill. Interestingly enough, no observed issues observed yet when driving in "sport" mode.

My wife has only driven the car about 50 miles since we unloaded the trailer, and I did another 10 or so while trying to diagnose the issue; my assumption is that the adaptive transmission "learned" the trailer and will just take a couple hundred miles to "re-learn" what shifting is supposed to look like without a trailer.

I have a cloned VIDA/DICE unit, which didn't show any error codes when I plugged it in. My current plan is to have the wife keep driving the car for a week or so to see if it goes back to normal, and if not, mess around with resetting the adaptive learning on the transmission using the DICE unit.

Anyone experience anything similar or have recommendations? If my theory is correct, I'm tempted to use "sport" mode next time I tow so that the car doesn't learn any more bad habits...thoughts?

Handy reference for anyone on here, in the VIDA software, if you go under the TCM on "activations", you can temporarily put the into a mode that displays gear number and alerts you when lockup occurs (as opposed to just showing "D") on the dash. I found this very helpful isolating where the problem was occurring, as it seems like the transmission programming on these cars is to lockup very soon after shift.

Thanks in advance,
-Dan

P.S.- even if I'm the only one on the forum with this issue, I will update once the issue is resolved in case anyone else here comes across the same problem later.