1989 F250 with 5.8L. Replaced the TPS due to high idle. Now the truck won't start. No lights, no horn, nothing. Charged battery. Didn't help. Getting 7.5V at the control side of the fender mounted solenoid with ignition on, so I'm losing voltage somewhere. When I disconnect that wire from the solenoid I get lights coming on on the dash (but no interior lights or headlights or anything else). I reconnect it, still lights. Roll the ignition, hit start, one nice click then nothing. No lights on the dash, absolutely nothing works. I've never seen anything like this, don't know where to go. This is a truck that's been patched together by the previous owner, a complete hillbilly. Any advice on where to go next would be very appreciated.

 

seems like a loose connection somewhere. i would start out at the battery and work your way to the main components of the ignition

 

Agree with last post from 80ford 302. A good place to start.