th400 transmission not shifting

The electrical connection is used strictly for forced downshifts, it won't affect the shifting if disconnected. The vacuum modulator controls the upshifting, I suspect your change to TBI has somehow interrupted the vacuum supply to the modulator.

Im sorry it will still shift I just dont have any forced downshifts.

If Edelbrock doesn't offer a solution and there's nothing in any of the speed parts catalogs, you're probably going to have to scrounge the junkyards and find something off of a mid 80s pre-TBI truck. 'Something' being the electrical switch that mounts on the gas pedal bracket.

You know whats funny I just did some reprogramming on the edelbrock tuner and its getting to shift a lot better with out that wire hooked up. But according to those mitchell wiring diagrams that orange wire supposibly goes to a relay and then goes to the slot on the factory computer that it says goes to to the brake switch. So Im wondering if that wire is just downshifting when I step on the brake. It is a 1 ton pickup.

Does it have a lock up torque converter? Many of them have sense wire from the brakes that unlocks the TC when the brakes are applied

You know I have no idea if has a lock up converter or not. I not even sure what a lock up converter does Im not to smart when it comes to transmissions?