My 04" 2500 4X4 will not down shift into 1st gear. This doesn't happen all the time and there does not seem to be any pattern to it. Also sometimes you can place the trans in park for a few seconds then shift down to 1st and it will work. Shifting from drive to 1st has never worked. Anyone have any ideas?

 

Mine did the same thing. It was the govenor solnoid in the trans.