I am wiring in a 12v heater and I need the relay to get it�s 12volt signal
(this will trip the relay, not power the heater) from a source that is only
on when the engine is running (ie. Once the alternator is cranking).
Ideally I�d like to tap into something in the little electrical box in the
rear engine compartment.  Wondering if anyone has any thoughts on the best
place to tap into?

Dave