ok so i installed a '96 vortec 5.7/4l60e combo. engine fires up 1st try. transmission is acting like an asshole. before i installed it i took the transmission to a tranny shop and had it rebuilt. after its all installed, it won't shift into 1st gear. i take it back to tranny shop and they hook up their test equipment and supply power to the shift selenoids and its shifting perfect. so basically the 1-2 shift selenoid is not getting a signal. so they hook up to the computer in the truck and the computer is sending the signal. so then we are assuming that there is a bad wire going from the cpu to the tranny. at this point the tranny shop just lets the truck sit there for about 2 weeks and do nothing about it. i got impatient and towed the truck home figuring its just a bad wire, i'll fix it myself. i drop the pan and connect an ohm tester to the light green wire that goes to the 1-2 shift selenoid and i connect the ohm tester to the opposite end of the wire up at the cpu, its conducting perfectly. now i'm stumped. the engine came out of a wrecked truck, so could there be some internal damage in the cpu to where the signal it is sending to the trans is no making it to the prong where the 1-2 wire connects to the cpu. please help!!!!!!!!!!