Relay, Electric Running Boards

Im trying to wire up electric running boards. They have a motor power & ground. when powered it open the running boards and when I reverse the polarity it closes the running boards. I want to wire them up to the interior lights on inside the truck. When the truck interior lights come on I want the running boards to come out. I haven't figured out how to reverse the polarity when I close the door and the lights come off. So when the truck inteior lights come on I want the running boards to come out and when the lights cut off I want the running boards to go back in.

Do they have internal limit switches?

ONLY IF THEY HAVE INTERNAL LIMIT SWITCHES SHOULD YOU ATTEMPT THE FOLLOWING. If you are not sure, do not attempt the following.

If so, 2 Single pole double throw relays wired as follows:
Relay 1, +12 to 87 Ground to 87A One side of your motor to 30 You did not tell us what vehicle so I can not at this time tell you what to do with 85 and 86
Relay 1, Ground to 87, +12 to 87A The other side of motor to 30.

If it is operating backwards reverse the wires going to the motor.

You need to ground or power both 85 terminals. connect both 86 terminals to the wire you are wanting to use at the domelight.