nluchau

I have never had my cooling fan run after a turn off of the vehicle. I have noticed it come on directly after I start the vehicle if its warm then it goes off after a short time. This is on my 5.3. 6.2's might have other metrics as to when the fan runs?

So about 3500 miles ago GM put in a reman transmission as a customer satisfaction for me. I still feel the firm downshifts but not as bad. The one thing I notice now ever since the 2nd transmission is the upshifting seems a bit firm. If its cold and I increase throttle and hit 33mph it abruptly upshifts into 5th gear. 1st - 4th seem fine just when it hits 5 it feels like it drops into 5 vs a slow ease into 5. I'm not heavy on the throttle either. I talked to the service manager right when I first noticed it, a few days after getting it back from repair. He said to give it 3-4k miles and let him know if it still happens as the transmission has a learning curve. One thing I've also noticed is the trans fluid (when checked cold) is way up on the dip stick overfilled. My question is what can the dealer do now with this abrupt upshift into 5. Would a tap reset, or any other reset possibly correct this? Thanks for any info

Funny you mention that: I've noticed if I'm harder on the gas before slowing my downshifts are way more desirable yet almost normal feeling. If I'm easy on the gas the downshifts are harsher when slowing.

Interesting and great info here mmmikkke! Thanks for this write up and yes I think this is the concern with our trucks and downshifting. I had my transmission replaced under bumper to bumper and it still does it. Now it goes into 5th gear at 32mph. I think this is a bit much. Let me know what your outcome is here.

Update: Transmission was replaced under bumper to bumper at 33xxx miles. I am still noticing harsh downshifts but not as bad, one other thing I noticed is the transmission is trying to get into the highest gear so darn quick. At 32 mph it will go into 5th gear?!?!? I've been told to give it 3k miles to have the transmission learn my driving. Still doesn't feel right to me.... I now have 35xxx.

Thanks for the replies so far. Much appreciated! Is it worth it to have the adapts reset or see what the dealer can do? Maybe another fast relearn perhaps? Not planning on going the tune route at the moment.

Dealer just recently put a reman 6 speed in my truck with 34k miles. Back story, I was having hard downshifting (jerky) and now that cleaned up a bit but what I am experiencing with the new transmission is this: If I accelerate slowly and hit about 32mph it upshifts with almost like a thump. If I accelerate faster it upshifts at about 40 just fine and feels normal. My observation is, its trying to get into the higher speed too quickly. Anyone experience this and is there anything the dealer can do for this? Is it still learning??? Thanks!

Do you mean the 8L90 and not the 6L80?

Same thing happened to my black truck and it was indeed bird crap. It ate through the clear and clay bar never did anything. Had it polished out but can still see where it was. This was on my 2016

Yes you need to disable grade braking at every turn on of the key and sadly this did nothing for my deceleration downshifting.

Duplicate post

I dont know if the dealer has ever done a clutch relearn on my 6L80, is that a thing if they reset taps they can do that? I know on the 8 speeds they reset them and relearn but I hear nothing about the 6 speeds. The TSB that talks about the 8 speeds having harsh 3-1 downshifts is exactly what I am experiencing with my 6 speed but it seems my issue falls on deaf ears. This is what I am referring to that doesnt pertain to my issue but I'm having almost the same issue. https://gm-techlink.com/?p=7170

Mine has this 2-3 hard shift (first one of the day) too. Then its fine.

My valve body and TCM was replaced already and the taps reset a couple of different times but that was all. I believe with the valve body the fluid was mostly all replaced? It's almost like its downshifting too early thus causing the rapid jump in RPM and the jerk/braking sensation because its not matching the speed.

Hey bud, was your's doing the jerks or was it actually clunking? Can you refresh me on exact symptoms again? Thanks!