ok on my 01 2500 automatic i lost overdrive. it will shift fine through all the gears but just will not pull into OD. i been doing some reading and it seems that this is a common problem but are there any other sensors i should look at or check?

 

RPM speed sensor on the tranny and the speed sensor on the rear diff as well. Theres also the brake light switch to check into but before all just to be sure try setting the apps voltage.