PLEASE HELP - My automatic transmission truck wont go into gear

This has happened a few times. When I release the brakes and go into drive it doesn't "get" into gear. How do I do a full transmission ecu reset? Where is the ECM fuse located on 2010 Peterbilt 386 and should I disconnect it or something to reset? Thanks so much for any help

 

Thanks for the responses guys. I've tried unhooking those blue and green fuse things in the compartment under the driver side door where the batteries are. One says "DE" and the others say "15" and it says engine fuse on it. I figured those would be the ones. I also tried doing the transmission reset where you turn it off and on quick 10 times. When this happened before it started working after like an hour the first few times. The last time it happened I stopped at a stop sign at an intersection and it happened and didn't work again until 4 hours later as the wrecker was on its way with cops right behind me telling me to get off their road. Luckily it wasn't a busy intersection, and luckily it happened at a rest area right now. It's been over 8 hours and nothing has worked. My company told me its probably the XY shifter, but whatever it is looks I'm screwed and will have to get it towed to a dealer. What a pain in the ###. I've only been driving a year and I've only had an automatic with my company, so I'm really not liking automatics at this point

 

Thanks I wish I had the know how for that but I don't. Anyway there seems to be an issue with the XY shifter or something deeper because it's had the "F" fault signal blinking off an on where the number of the gear you're in is for a while and when I turn the truck on it doesn't do the whole routine where you hear the brakes release a few times. Something is messed up