98 Caravan OverDrive Shift Problem

I have a '98 Grand Caravan SE, 3.3L. Van runs great, except... Often times on the highway when I start up a hill in 4th gear (or Over Drive) the transmission will shift down to 3rd for more power. This works fine. However, once I reach the top of the hill, it will not shift back up into 4th gear. It stays in 3rd gear. The only way I can get it to go back into 4th gear is by pulling over, stopping, turning off the ignition, and restarting the van. The van will then go back into 4th gear just fine, until the next hill.

When this occurs, I do get the "check engine light" with codes P1776 and P0700.

Thanks for the help.

Do you have dex-III in your tranny?

Brian
AwPhuch

Not sure if I have dex-III. I had it serviced at AAMCO ~ 1yr ago. This problem was happening prior to AAMCO servicing this. I will try some of the things in the links you sent me, starting w/ a changing out the fluid. I should use ATF3 or ATF4, correct?

For a '98 you can use ATF+3.
I use Amsoil myself, one quart ATF+3 and the remainer Amsoil.
I have a '00 which requires ATF+4, a couple of years ago one of the hoses came off and dumped all the trans fluid. The local mechanic put Amsoil in it and it worked better than ever, except it shifted a little harder than a liked. Later the pan gasket started leaking so I tightened it up and had to put in a quart of ATF +3 b/c that is all I could get. The +3 smoothed the abuptness out and I have been running this combo ever since. Now have 145K miles on this trans.