Bad Transmission Sensor? 4R70W
 

Hello,
I just rebuilt my tranny and I finally have it installed in my truck today. The only problem is that when I select gears it goes sparadicly into any gear. The only gear that works is 1st 100% of the time. Drive sometimes work and somtimes not as well as reverse. Park as well works 100% of the time. I was wondering if a bad sensor would cause this or do I have to reconfigure the gear selector on the tranny. There is also enough of fluid in the truck. That was the first thing I looked at. Could have me welding without taking off the neg battery cable sorted it out. Also the only way I can start up the truck is by bridgeing the starter relay.
Thanks,
Brian