Got kinda A wierd problem

[Chevy43]

I have a 1994 Chevy 1500 4x4 and just got done swapping out the 4.3 V6 in my truck to a 350 V8, ever since I've swapped these motors around, my brake lights on the rear of the bed (not the one on the cab) do not work at all when the ignition is on, nor do my windshield wipers. But when the ignition system is off, the brake lights work perfectly fine. And when the key is in ACC the wipers work just fine like they should?? And i know the that wipers are supposed to work when the key is in the on position and the the ACC position. The 3rd brake light works fine because it's on it's own circut I'm told. Also my Parking Brake light on the dash board just kinda glows, and when I hit the brake the light basically goes out? Could it be the ignition switch? Please help thanks

[Ccolvin]

make sure you connected the engine to ground strap. You may have to search out the electrical...I found it best to start at the battery and work your way toward the fuse panel. You may have crimped a wire somewhere in the installation or cut it by accident, setting up a short. Don't think it is the ignition switch, but we just went through a october-January search for a weird electrical problem and ended up sending it to the electrical shop-took them a week to find it.