Hey Mayoman, There is a factory alarm on your 84 that disables the fuel pump circuit and (I believe on some cars) blows the horn through the "Z" connector of your fuse panel - but your starter should still be able to spin over the motor. I had a couple of wiring issues on my 84 that spooked me a bit so I disabled the alarm using the instructions recommended in the maintenance manual.
If you would like to eliminate the alarm while troubleshooting and rechecking your previous troubleshooting steps - You need to:
1 Locate the "Z" connector on the fuse panel. They are alphabetically labeled.
2 Pull the "Z" connector (outer half) of the plug toward you - until the two halves separate.
3 Locate pin #6 and #4 within the fuse panel side of the "Z" plug and install a jumper across them. I used a short pre-cut piece of wire and crimped a couple of terminal lugs to the ends for the jumper.
4 Leave the outer half of the "Z" connector plug loose - you might zip tie it securely to one of the other wire harnesses so it doesn't move around.
Like I said - this procedure prevents the factory alarm from signalling the computer to shut down the fuel pump relay and the ignition CD box. You might verify that your battery terminals are clean, then connect a mechanic's external starter switch directly to the back of the starter terminals to make sure the starter is good. If the problem continues, the best guess is that you should probably back track the preventative measures you listed previously.
Hey Neil - Plugging in a relay back into the wrong socket may very well be powering the horn, Good Call -
Good Luck, Michael
