Originally Posted by denis1278
Yes, it was in the "P" position. If the driveshaft is rotating, would that mean that the parking pawl is not engaging?
Typically, yes, if the rear
driveshaft is rotating, that means the parking pawl is not engaged. Note, however, that if something is broken inside the transfer case (between the transmission and the rear driveshaft) that could allow the driveshaft to turn, even if the trans is in Park. Of course, I'd expect that that would also give you "no drive any gear", so I don't suspect that's your problem. However, do you normally drive in 4x4 mode? Will the truck drive in 2WD mode? I guess if your transfer case output (to the rear driveshaft) was broken, it's possible you could be driving the truck through the front driveshaft (only), and then you could have no Park, depending on the transfer case design. But you'd think the dealer would have found that.
The best way to prove conclusively whether the Park mechanism in the trans is functioning or not is to monitor the trans output speed (using a dealer scan tool) while it's rolling (in Park). Note that the key would still need to be ON for the PCM to remain "alive" and be broadcasting this speed. If the speed reads zero, then your parking pawl IS working and something is broken (or slipping) beyond that point. If the speed reads some positive value, then the parking pawl is not engaging.
Your dealer may be able to loan you a scanner (called a Wi-Tech tool) that can be programmed to record your transmission data. I believe they can set it up with a trigger button, so you just let it monitor continuously, and then when you get the "rolling in Park" you hit the trigger, and it saves the previous 30 seconds (and the next 30 seconds) of data, which the dealer can then download and examine. Have them set up a recording template which includes turbine (input) speed, output speed, current gear, PRNDL position, and wheel speed readings. Then maybe you can "catch it in the act" and see what's going on.