Ok i have 2006 rcsb was a 5.3 flex, now me an some buddys have installed my new built 6.0 Boost motor everything i can see is hooked up I've looked over it twice Charged 2 batterys checked grounds resurfaced spots were the grounds go. An the fuel pump doesn't come on when i turn the key on but when i turn it off it does for a sec. Then my gauge lights stay on all the time for some weird reason. An we can jump the stater relay it turns over fine. I hook hptuners scanner up it just says please turn vehicle ignition on. I'm stumped I know this is probly some simple but my luck isn't so great. The brakes lights blinkers work fine. the truck has been sitting in the garage for AWHILE though no one has really touched it or anything.

 

Look over it again and make triple sure ALL the grounds on the back of the motor/ heads/ trans bolts are hooked up. Also, make sure all the wires are on the starter. Sounds like a missing ground though. Theres also the ground on the bottom of the block.

 

Went over the grounds tonite checked battery I'm stumped anyone no were the grounds all are for sure my power windows an stuff don't work but lights do.