85¹ Olds Firenza electrical short somewhere

I have a 85¹ Olds Firenza (Buick Skyhawk, Chev Cavalier, Pont Sunbird)
that has a electrical short somewhere. When the short happened I heard
a loud pop sound from the radio speakers and the fuse blew. The short
is on the circuit used when 12v is always active (when the engine is
off -hazards, horn, interior lights and clock). I unplugged every
possible component I could find on the wiring diagram, but to no avail.

Here is a list of what I removed from the circuit: Radio, Lighter,
Door ajar, horn, all lights, steering col switches. I haven¹t tried the
horn relay yet. To save me sometime, has anyone else had the same
problem, and if so what was the culprit? 
Thanks
R