Quote Originally Posted by robg2001ls1 View Post
I m working on my 5.3 swap in my 87 swb chevy. I just got my harness in last week was done by chevy thunder. I hooked up all engine sensors and i am a little unsure about the last connections.Mostly just a good source on this truck for 12v switched igntion. I have the constant 12v from the harness hooked up to the starter and i tried hooking up the 12v switched ignition to an empty space on the factory fuse box under the hood labeled" ignition". I did get it to crank a few times but then i cleaned up some of the connections and re routed some of the wires. Now i cant get the darn thing to crank. There is a wire on the harness labeled"igniton power".I put this to the igniton slot on the factory fuse box. Im pretty sure after i cleaned up my wiring i used the same connection points when the engine was cranking.I just dont understandwhy its not working now. Im sure someone has done this swap on the same style or year model truck. Any tips or help is appreciated?
The switched 12v ignition wire sould not be going to the fuse and the constant 12v wire should not be going to the starter. If you left your old trucks wiring harness in tact then hook the starter up exactly how it has hooked to your old starter. The bigger wire for power and the little one for the ignition signal.

The ignition wire needs to go to the acc on signal on your ignition switch. which is probably purple or pink. It will have 12v when the truck should be running and should have under .5v when the key if off and out. This wire has nothing to do with cranking the motor.

The 12v constant wire should be getting exactly that. 12v Constant. Either hook it to your old battery junction block or hook it to anything that will always have 12v to hold the timing memory in the computer.