This is a followup to a thread that I posted, called "Accessing switched (accessory/ACC) power for aftermarket devices). It's desirable to tap into "switched" (not always-on) circuits like this, so your aftermarket gadget doesn't drain your battery.
That thread gave details re. how to tap...
For powering aftermarket add-ons, it would be nice to have access to switched power (ACC, or accessory power) so the devices can’t drain the 12V battery when car is off. (Honda calls these circuits ACC so I am going to use that term even though they also use ACC for Adaptive Cruise Control.)...