I am installing a set of the Recon door sills on a 2008 F350 for a buddy of mine. He got them second hand and has no instructions. Does anyone know the polarity of the power wires?

I already have a relay wired up to the interior light circuit for power, all we have to do is run the wires close enough for the stock wires/power boxes to reach.

 

As it turned out the wire leads were tagged + and - so we got pretty lucky. To answer my original question (for anyone researching this topic later): the ground wire (-) is the one with the stripe and the positive (+) wire is the blank one.

Another couple of notes:
The wire I tapped was the yellow wire with a gray stripe on the top bundle of wire going in to the fuse block under the passenger side foot well. This is the same wire that supplies the lights in the head liner I believe. The catch to this set up is that circuit is not an "on/off" circuit. The voltage drops off slowly when the circuit turns off = you'll notice that the factory lights don't flick off - they "burn out". This creates a bit of a problem with running the coil on the relay in that the voltage around 7-8 makes the coil buzz and the contacts slap in the relay. Once the voltage is low enough that the spring holds the relay open it is fine, and likewise when it is high enough to keep the relay closed it is fine. I'm thinking of making a solid state circuit to drive the relay coil instead = it will make the relay last longer, and the solid state circuit, without going crazy with it, won't take the current that the relay will (not that these Recon lights pull any real current, just for future expansion.

I am not sure what the circuits are that are on the power wire to the light panels, but what ever they are if you can hear high frequencies these things may drive you crazy. Be forewarned.

When I get a picture of the wiring I'll post it up for reference as well. I didn't think about taking a picture this evening...