Radio runs on acc. Could use radio power lead to energize a relay, that routes power to your accessory.

 

so “add a fuse” to radio? And spade connector to the “BATT” fuse on the modifry pic?

 

so ACC wire won’t work on the IGN switch?

 

Along with a relay. Add a fuse tap goes to relay coil, to energize it. Batt spade lead goes to one of relay normally open (NO), other NO goes to your accessory.

Relay doesn't take much power to energize. So can still power radio.

 

So one of these before connecting will protect it ? I think the only reason the “always on” needs to be connected is for the date on the camera

 

Yes. You need one of those for both taps. The always on is probably a very low current just to maintain memory. So guessing like a 1A fuse would be enough.

 

You can definitely wire the ACC wire to the IGN connector - the radar detector won't turn on unless
the engine is running, but that doesn't seem a big problem with a radar detector.
I had an audio accessory switched off the IGN connector, which was a little annoying because I couldn't
listen to it while parked with the key in the ACC position.