Hard downshift after tranny fluid change(2001 GC)
 

Transmission was working fine but I thought I should change the fluid and filter. Changed it and everything went fine(very fine shavings on the magnet) but went I started driving it again it downshifts really hard from 4th to 3rd gear. The same thing happened to me with only 50K on the vehicle(now it has 150K). I took it in to my local oil change place and they changed the fluid and filter and it messed up the shifting. I ended up taking it to the dealer and they changed the fluid again and said they had to adjust the bands. Why would just changing the fluid mess up the shifting or require band adjustment? Anybody have any ideas?

Hard Shift
 

My question is what fluid did you use for the change, was it ATF+4 or was it DEXRON or MERCON ? The wrong fluidm can cause shifting problems, though generally a lack of shifting until the fluid is warmed up is the usual problem.

Oh, buy the way. your transmission doesn't have bands. its a 4 speed electronic transmission. Any way it starts by using ATF+4 fluid. There is a flash for a harsh 4/3 down shift, and you may want to do a quick lean too. Thats to reset the CVI specs to factory.

Hard downshift
 

Thanks for the input VaBear. I did use ATF+4 but didn't use Mopar fluid, I used a store brand. Someone suggested that may make a difference but it doesn't seem that it would? To do a flash or the other adjustments would probably require a dealer? Thanks for the input!

Hard Downshift
 

I do not believe non MOPAR ATF+4 is a problem as Chrysler does not make its' own fluids (or many other parts). I use Quaker State or CASTROL ATF+4 in my '96 and Purolator filters and have since day one and I have no issues with the transmission (I did have her rebuilt at 117,000 miles but I do not beleive the fluid was an issue).

Just had this happen to our 03

the computer has to be reset for the shift patterns

took it back to the shop he did it and now it is great again

I just had the same problem with my 02 GC. I freaked out and thought the tranny was on the way out. It had an abrupt down shift when slowing down at approximately 30 mph. After a few weeks it faded away to nothing. I hear it has something to do with the computer recalibrating when the fluid is changed. Just give it time and it will go away. took about 1000 miles of driving but now the shift is seamless. 120k on original tranny. I change the fluid myself every spring, use the cheap atf4 from walmart