back up camera wiring assistance needed

this isn't going on my avy, i already did that...easy cheesy. I'm adding a back up camera to my wifes van, on every other vehicle i've put a camera on, i just use the reverse lights to power the camera and for the camera signal for the head unit. I have a problem with the windstar though, both of the wires to the reverse light have 12v at all times, unless i put it in revearse. So when I hook it up it locks the radio in reverse mode. The van does have the backup sensors, so am i missing something, or do I have to wire it up another way.

If your lights have 12 volts all the time and only come when in reverse, then you have a negative logic system. (I have not seen one for lights, but it it easy to get around)

So hook up the 12 volts to your power, but do not hook your ground direct, your lights negative side is where this needs to go.

The ground will do the switching of on/off.