'05 Deville Tranny Issue

[Farmer Lary]

I pulled up to our local city hall to drop off a bill. I put the shift lever into Park and started to get out. The car kept creeping forward and I noticed the indicator on the dash was still showing "D". I ran the shifter through all the positions, then back into Park and it quit creeping, so I assumed everything was alright. After I dropped off the bill, I put the lever in reverse and the car kept creeping forward. It was then I noticed the indicator on the dash was STILL in Drive. I shut the car off, ran the shift lever through all the positions again, and I think it went into Park. I tried to start it, but it wouldn't turn over. I turned the key off, messed with it some more, and finally got it into neutral so I could push it back away from the building. I tried it several more times, the dash lights would come on, but wouldn't turn over. Any ideas? I would greatly appreciate any input! 

[Bruce Nunnally]

There is a switch that translates the movement of the shifter to changes in the transmission.  It is commonly called the PRNDL switch for fairly obvious reasons.  The long name is "Neutral safety and range switch".  What you are doing is the right temporary fix -- to safely run the shifter through all positions to try to 'jiggle' the PRNDL switch back to life for a bit. 

This video shows the part and kind of shows the rough area it is located -- check around 3:00 in.

The long term solution will be to diagnose exactly what the 'disconnect' in the shifter is.  It may be as simple as replacing the PRNDL switch, but you will want to investigate and diagnose first.