Almost everything on the car, short of the lights,is in some way controlled by the ignition sw.If your sw is in the bowl, there you go; Put an ammeter in series with the battery plus, and start unplugging stuff.
The biggest draws on that switch, are probably the heater blower motor and the alternator field circuit. If you have wired your start and run circuits together, for the ignition, you may be powering up the starter solenoid full time.IDK
What are we working on? 70upA?
