Originally Posted by mattdel

Oh.. right.. 1990 has the S wire going to the solenoid instead of the starter.... my bad.

For my idea to work you'll need to convert to the 1993+ mini starter, otherwise I'd say you should probably use the new wire you installed to power a relay, and splice off the headlight circuit to switch the relay, sorta like the fog light fix.

I can't stress enough that this needs to be done correctly. Fox wiring is precisely the size needed to power the intended circuits (sometimes too small, too). Splicing a direct power feed from another fused circuit will cause problems, 100% guaranteed. Dash fires are the the quickest spreading.