I want install a kill switch on my 1st gen, can anyone help me locate the wire that I need to tap into. (color too) Couldn't find anything specific to 1st gens with the search.

 

My son's 85 (EFI pickup) has the wire harness running under the passenger seat. The wire should be Blue (caution: there may be more than 1 blue wire there). There is like an 8 wire plug under the seat on his.

 

there is an access panel underneath your rear seat. Open it up and you will see the wiring harness. One wire is the ground wire, the other goes through the lid of the gas tank to power the pump, that is your wire. Go underneath the truck, and you will be able to follow the wires. There is a harness where it plugs in. You will see the color of the wire, and all the places you could tap into it. I don't know the best place to run the kill, but that should get you started. You could also kill the wire to the circuit opening relay near the ECM, but that would probably be more work. Good luck.