Topic: Boss 302 unusual wiring

[midlife]

You will find that plug used on all 69 and 70 Mustangs with AC, as that is the lead for the AC clutch.  The question is: what was it used for, if at all, for non-AC cars?  I have two examples from B2's, one of which I know is late 69 production.

[J_Speegle]

You will find that plug used on all 69 and 70 Mustangs with AC, as that is the lead for the AC clutch.  The question is: what was it used for, if at all, for non-AC cars?  I have two examples from B2's, one of which I know is late 69 production.

Yes in looking on non-Boss applications I also found it as a AC connection. At this point I don't think it was used at all for the Boss 302 just like other options when not purchased on other cars the support wiring was included in the standard wire loom and just not connected to anything. Saved on making individual different main looms for all the different possible combinations

[midlife]

Yes in looking on non-Boss applications I also found it as a AC connection. At this point I don't think it was used at all for the Boss 302 just like other options when not purchased on other cars the support wiring was included in the standard wire loom and just not connected to anything. Saved on making individual different main looms for all the different possible combinations

I almost agree with you.  Two things stand out: it WAS connected to something: the RUN-only ignition line instead of the standard AC switch.  In addition, since the heater box was for a non-AC system, the heater extension harness was different than the AC version (the heater boxes differ in where the resistor pack is).  This suggests that Ford knew that there was a reason for using a modified AC underdash harness for Boss cars by having the wiring manufacturer cut the AC line, splice the outgoing line to the ignition switch line, and providing a non-AC heater box extension harness.
The only other thing I can think of would be a hood-mounted tach that would use the RUN-only line to power it.  I don't think B2's ever came from the factory with a hood-mounted tach, though...