1995 Bonneville Transmission

[JJ052653]

I just started having problems with my transmission not shifting gears in Drive (no overdrive) when starting out. This problem does not happen all the time. This morning, I had no problem shifting while in drive. However, yesteday, the car would not shift out of first while in Drive. I pulled over and stop, then shifted in overdrive and the car shifted fine. I then shifted back into, drive and the car had no problem. Anyone else having this type of problem ? Car has 156+ miles on it. Any help would appreciated.

[Jim Adams]

take alook under the car and find out what type of trans you have,,see if 4T60E is stamped in big letters on the pan,,,thes etransmissions are electronicly controlled and you should get a service engine soon light comming on at times when your problem is happening,,if so have auto zone check it for trouble codes they do it for free,,if you dont have the 4T60E trans then you have the 125 w/overdrive and it may be the overdrive switch located on the side of the bellhousing in the front above or below the modulator valve,,if it is the 125 unplug the switch and test drive if car operates ok except no O/D then the switch is bad.Usually in the 4T60E trans it is the vehicle speed sensor or one of the input or output sensors that make them shift funny or do not drop into lower gears,,also the modulator itself could be bad,,does the peedo get wacky at any time during its malfunction?

[daman]

Has the trans ever been serviced?

[JJ052653]

Had the transmission oil change at 90,000. Car has 157000 miles. This problem isn't happneing now. When it does happen, I notice the transmission is trying to shift from 1st to 2nd.