So I'm about to pull out what little hair I have left on this one. My son has a 1995 F150 with a 5.8L E4OD trans. 210k miles. The truck started hard shifting between all forward gears. It progressed to horn will not work and will not start. It'll crank, but not fire.
Keep in mind, this same thing happened about 3 months ago after we replaced the front fenders and core support (maybe 2k miles ago) and miraculously cured itself. During that episode we changed the VSS, but the problem remained. One day while still trying to figure it out...and despite not changing anything additional, the truck decided to run and everything was great for 2 months. Now it's back.
Mechanically, within the last year, for different reasons, we have changed all fluids and filters, tune up (plugs, wires and cap), vehicle speed sensor, PCM (had leaking capacitors or resistors inside), temp sensor, new exhaust including catalytic converter, rear tank with sending unit and fuel filter.
I don't hear the relays clicking on either the fuel or horn relays. I also don't hear the pumps priming when cycling the key. No blown fuses in either fuse panel. We pulled the column cover and confirmed the OD switch wiring shows no signs of shorting and clock spring appears to be fine. Is it a coincidence the Fuel, horn and PCM relay are next to each other in the underhood fuse panel? That is the only thing I can see they have in common. If you hadn't guessed, I'm not great at electronics.
Any ideas? Greatly appreciate any advice.

 

So we figured out the no-start issue. My son took off the gauge bezel which included the dual tank selector switch. In case you didn't know...it wont start unless that switch is plugged in. It's a learning process.
Keep you posted on the horn and hard shifting issues

 

I'd test the horn relay and check for voltage, along with the grounds. Might even be a bad horn from water ingress.

 

Buy one of these Ford OBD1 code scanners:


Here is a code list:

https://www.therangerstation.com/tec...gitcodes.shtml

 

Figured it out. The horn negative and vss/rabs positive run through the speed control servo amplifier. That had a poor connection at the plug. After tightening the pug connections all is good. Horn blows and trans shifts perfect thanks for your help

 

That'll do it! PCM sees no VSS, transmission gets confused. You probably would have seen a VSS code if you had a reader.