Check for continuity coming from the switch from the "start" position. If it is good, then the starter is defective, or a loose wire somewhere around the engine.
try replacing your your park neutral safety relay
Try replacing the kill switch relay.
try replacing the delta pressure feedback sensor. this fixed my explorer.Or you can try replacing the relay.
The fuel pump AND fuel relay (the relay being located under the steering wheel area under the dash and fuel pump located in the fuel tank) went out simultaneously causing my '94 Legend not to start at 150,000. After replacing the fuel pump, having the relay repaired and replacing the fuel filter, which is a good idea to replace the filter every year and right after replacing the fuel pump, mine started right up and I haven't had any problems ever since.
I would start with replacing the signal flasher relay.
It could be a loose battery terminal or dead battery! A faulty starter solenoid/relay will often only click once when tryong to start the vehicle.
Try replacing the ECM relay in the box under the hood.
the starter motor needs replacing
Start by replacing the Flasher Relay.
when you unhook the battery the computer probably resets itself.
1985 doesn't have cold start relay.
Check the starter relay on the right side above the fender the little red wire going to the top sometimes comes loose