Underdash LEDs
 

Looking at wiring up some LEDs under the dash. I’d like them on only when the car is gone. Anyone know which wires to tap into? Thanks.


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I used to have some that were connected to the light in the push start button, if that's applicable to you. That way they were on when I got in the car before I started it, and when the headlights are on.

Do you want them just to be straight on/off? And do you want them to be triggered at the same time the headlights come on? If so, tap into the Illumination wire behind the radio. If you want them on all the time when the car is on, regardless of the headlight state, and turn off when you shut off the car, use the ACC wire behind the radio as the trigger instead. The radio wiring is the easiest source for that type of trigger.

BigTuna's suggestion is also a good mention if the ground circuit isn't BCM controlled. I bet it is, which isn't to say you can't do it, but there is a risk of damaging the BCM if done improperly. The radio wiring doesn't carry such a risk.

It also gets complicated if you want them to fade in and fade out like the dome light does. That requires tapping into the interior light system's ground wire from the BCM which again is a bit riskier.

I would be happy if they just come on and stay on when I start the car


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I would keep it simple then and just tap into the ACC wire for the radio.