I own an 05' Sunfire and I want to install some under-dash lighting that will light up at the same time that the interior dome light is on, both when the dash switch is turned on and when a door is opened. Where are the wires located under the dash that lead up to the dome light that I can tie into? Also, there must be a relay located under the dash. It seems that when the doors are closed and the light is off, there is 12 volts at the interior dimmer switch.... and, when the light is on or a door is open, there is no voltage present at the dimmer switch. Can anyone help me with this ?????

one wire would be off the door sensor (not sure if it's high or low when the door is open) so you might need to use a relay .. and for the dash lights there's probably a wire on the dimmer switch you can tap into, one of the 4 wires. use a meter to test

14.82 @ 97 mph

dude man theres a few places you can tap into to operate the the lights off dome light, one place is the drivers side kick panel theres a light green/black wire you can tap into (think this will only activate it for that door though?) or you could remove you a pillar on drivers side and tap into those two wires ones white and ones orange hope that help oh and i think the orange is (+) have a great day!

The only problem I found with tapping into the dimmer switch is that there is no voltage present on any of the wires leading into the switch. I was already planning to use a relay, but the relay should be not activated when the doors are closed. There should be no voltage activating the coil of the relay. The relay coil should be activated only when the doors are open or the dimmer switch is turned on.

Find the wires at the dome light and tap into those. Then run the wire back under the headliner and down the A piller, under the dash. Instant power when the dome light is on