Yo rogmit,
Good that no one was injured!
With all battery posts, connectors, and ground cables clean,
since the relay on inner fender clicks, the path from ignition switch through clutch pedal positioning switch Jumper, with or without anti-theft module, to transmission range sensor aka MLPS sensor for E4OD, and to starter relay coil is Good.
Suspect relay.
Can measure voltage on starter side of relay that is #2 in this pic by Shaun, if battery voltage is there with key in START position, relay COULD BE GOOD, but not able to pass full current to starter or its solenoid atop starter.
Read this by BLADE262US at
http://broncozone.com/topic/7446-94-bronco-starter-replacement/
The pop-up ad here is killing me, it interferes with my tablets pop-up keyboard.
http://broncozone.com/uploads/monthly_05_2012/post-18998-0-78492700-1338357203.jpg
Or,
With gloves and eye protection lay a heavy ***** driver across both relay posts to send power directly to the starter. If starter spins replace relay.
The starter solenoid (11390) performs two functions. It shifts the starter drive pinion into engagement with the flywheel ring gear and connects the starter motor to the positive side of the battery.
The drive pinion is shifted through a lever which is connected to the solenoid plunger. The electrical circuit between the starter B and M terminals is closed by a contact disc which is also attached to the solenoid plunger.
Movement of the plunger is the result of a magnetic field generated by the pull-in and hold-in windings contained in the solenoid.
When the key is turned to START, current flows through both solenoid windings. This creates a magnetic field strong enough to pull in the plunger, shifting the overrunning clutch and drive pinion into mesh with the flywheel ring gear. As the plunger nears bottom it strikes the contact disc and forces the disc against the starting motor contacts. This completes the battery circuit, and the starting motor operates.
When the contact disc closes the contacts, the pull-in winding loses its effect due to the voltage being equal at both ends of the winding. The hold-in coil continues to hold the plunger in the closed position and reduces the current needed by the solenoid. When the ignition switch is released, the current to the solenoid stops. The springs within the solenoid open the starting motor circuit contacts and shift the clutch and pinion assembly to the at-rest position.
http://www.diesel-dave.com/vehic/manual/stj/images/j6403a.gif
During engine cranking, the drive pinion is locked to the output shaft through an overrunning clutch. When the engine starts and picks up speed, the overrunning clutch allows the pinion to spin freely on the cranking motor driveshaft, preventing the engine from driving the cranking motor. This protects the armature from excessive speed during the brief period that the starter drive pinion gear remains enmeshed and the engine has started.