1999 Pontiac Montana - Transmission

I have a 1999 Pontiac Montana with approximately 117,000 mile. For some time now, I’ve experienced a hard jerk as the vehicle shifts out of the lower gears. I have taken it to a dealer several times but short of tearing the transmission down, they have failed to find any thing wrong. Recently, I had the transmission replaced and every thing seemed to be running smoothly. However, in the last several weeks, the shifting problems have started again. It doesn’t happen every time

the vehicle is driven but it is extremely irrating when it does. Before taking in back to the shop, I was wandering if anyone can tell what the problem might be.


The problems in the carberater its not carbing its not carbing because the chingaso is ziging when it should be zaging

What the heck are you talking about?

hes being humorous,…overhaul time

willwoo50, you’re speaking of ‘harsh’ shifting?

Is the tranny you had replaced a new one or a rebuild?

I got lucky with my 2000 Silhouette with the same tranny in that I had the fluid and filter changed twice within 50 miles and the ‘harsh’ shift disappeared.

Yours on the other hand seems to have followed you.

One problem these trannies had was a pressure control solenoid that when worn, quits working, then the harsh shifting starts.

This solenoid is inside the tranny however.

One thing you may want to check is the VSS (Vehicle Speed Sensor) as it may be faulty.
JMHO is all.

Have you tried scanning the computer for codes???


Yes, with no results.

I could’nt afford a new trans. Soon after shift problems, changed filter and fluid, problem still there. A new problem reguired alternator and battery replacement. My tran. problem was gone for about 2 yrs. On a 1200+ mile trip, problem is back. Could be speed or throttle position sensor.

I am having the same exact problem with my '99 Montana. Did you ever figure out the exact cause??