how many miles on it? i would check all the fuses, also swap the trans relay with the ac one or something, if that doesnt work, get a new output speed sensor, if thats not it you probably need new electronics in the transmission. 47re's are great, i have one behind my 02 2500 that just dyno'ed at 550 hp and maxed out the tq reading, and thats in street trim. Guess what, its all on stock clutches and being abused for over 60k miles.