Does the vacuum pump effect the shifting capabilities of the transmission? I have a 1996 12v 2500 4wd and recently it started not shifting into 3rd gear. It just dawned on me that at about the same time I developed a vacuum pump leak that caused braking problems. i was wondering if the transmission uses vacuum to shift??

 

Nope.

 

That was a GM thing.....never mopar. Depending on what tranny you have....47RH or 47RE.....your tranny is shifted either by "H"ydraulic input, or "E"lectronic control.

 

Shifting issues are commonly due to wear in the TPS (Throttle Position Sensor). There are a large amount of posts here on that with some quick checks and fixes as well as suggested to just replace it. A quick search will have you busy.

Cheers.