Wiring lighted running boards

I have a 2006 chevy tahoe and I had some running boards installed but I tried to find the interior light connections inside and I can not find them. If someone knows where to find them or where I can tap into your help would be greatly appreciated. I am trying to get the running board lights to come on when the doors are open. Thanks again

Seth

I already ran underneath the tahoe. And the way it is set up is they both connect to each other and in one cable come up through the floor and only two wires left to connect to the inside lights. Yes I do know how to wire a relay. But I just don't know where to tap off of. You said run it off of the grey wires in the door. If I wire a relay what color  is poss and what color is negative. It really doesn't matter to me if they both light up when either door is open just that they turn on when the door is open. Thanks for the tips but a little more hints would be appreciated.

You can get a wire thru that molex plug...no problem, pull it apart, you'll see. Get 12v for the relays in at the ign. harness Pin 87 and 86. The door pin wire from inside the door goes to pin 85. Pin 30 goes (it's 12 volts remeber) to your lights. OR if you want you can wire your lights HOT, and use the relay to throw a ground, instead of 12 volts. Just swtch pin 87 to ground.

I tried to get that molex plug off before and that was a pain is there any tips on how to take that off? And if I take the 12 volts from the ignition then when I park the car and turn it off how is the relay going to be energized? And when I get in the door I can just tap off the light in the door right?