[edit after the time limit]
I'll be honest, the CDM radios were always a little bit wacky. Mobiles that did the low battery beep for no warning, occasionally one would lose a ground in the radio and it would ground thru the antenna causing all kinds of havoc, amnesia events when you'd power one on and find half the codeplug missing, IGN SENS circuits that would actually
power on the radio if the vehicle battery voltage dropped too far when the vehicle was off, thus killing the battery faster, I even heard a story of one powering on a radio via
just the ignition sense pin and ground - wouldn't transmit but it lit up...They're not a spectacularly great radio line, all things considered.
They worked, they're best suited for taxi cabs (yet they ended up in emergency service vehicles nationwide due to their price point), and most of the time the dealers were
more inclined to just replace a funky one than they were to pop the chassis top and try to find out which component was causing the issue...for several hundred dollars a unit, it made sense. Who knows, maybe moto knew something and figured a 3a fuze would prevent catastrophe farther up the line? I'm kind of glad we're done with them.
and i apologize for completely digressing from the OP topic at hand of finding an ign sense circuit on a '12 Ram 1500.