I see there are differences between 'ILLUMINATION' (e.g. +12V when the headlights are on) and 'DIMMER' (some sort of varying voltage.) I have read countless horror stories, particularly on Toyotas where connecting the illumination wiring on an aftermarket HU incorrectly causes the TAIL fuse to blow, loss of dash lights, and permanent damage of the dimmer control. I would rather avoid all that by staying far away from the circuit the interior lights and dimmer switch are on.
My new Metra 70-2003 wiring harness adapter only has an orange wire labeled "ILLUMINATION LIGHT" in pin B12. This coincides with "Park Lamps Input" according to the manual.
So is my assumption correct that this just gives me a 12V when the lights are on? Or do I need to look elsewhere? I'll take the meter to it when I go to do the install to verify but was curious if anyone knew off hand.
Another twist I think I'll add is a switch to turn off the input coming from the parking light signal. I think they fixed this in later models, but the 2003 with original DRL relay has constant problems with the ALC kicking all lights on during bright days when the 'A' pillar casts a shadow on the ambient light sensor so that would make the radio hard to see during the day. This way I can retain the brighter daytime settings as needed while driving with the lights on whether by my choice or the car's.
Or i could just run 12V to that switch and then to the radio's illumination input and switch it manually as needed. I could wire that into the radio's switched power and not worry about introducing any potential problems with the tail light circuit.
Thanks for any input you guys may have.
