polarity reversing with relays for 12vdc

So how will it reverse when the ignition is turned off? For the second relay use a 528t timer relay as follows: Ignition to black white. 12v+ Constant to red and brown, fused at whatever the motor's rating +2amps. Share this fuse with the other relay (terminal 87) Ground to orange and black. Yellow to motor wire. Set the timer for 1 second longer than the motor's time. This will save your battery. N.B. You could always salvage the timing unit from a late Hirschmann 6000 or Bosch Autojet antenna.

Howie, thanks for the question.  I knew that if you could not see how it worked, there must be a problem.  I went back and read my post again.  Then I saw the problem. 

EDIT  In earlier post, Relay A should be as follows.  Power to 87 and ground to 87A

Relay B should be ground to 87 and power to 87A

In the earlier post I inverted the order of power and ground connections.  But did not invert the data for those connections.

Point taken Craig, just that I won't assume internal limit switch based on the poster's (lack of?) knowledge, thus a timed relay when ignition is shut down. Come to think of it, if no limit switches one would need 2 x 528t timers to be safe.

Just saw your last post, NOW I see it! It's actually a very simple question, just not posed in a straightforward manner, always half the battle.

Thanks for all the replies. I will try tonight. and I will post the outcome.

Without any timing control from the relay circuit, your actuator will be powered up continuously whether the car is on or not. Your actuator will have to have limit switches to cut power on its own. Is this actuator you're referring to a simple power antenna or equivalent? You want it to extend when you turn the ignition on, and retract when you turn it off? That isn't how you described it originally, which suggested power was to be applied when the ignition was turn on, and the polarity reversed each time the ignition was cycled off and on again. That was the reason behind the inverter circuit like Oldspark suggested.

Back to my comments about using 2 x 528t timer relays instead. Else flat battery and/or burnt out motors.