I have tried two new switches, the car starts fine in park & neutral. the back up lights will not come on with everything hooked up. It is getting power from the one side but is not closing the loop and sending power back to the power block on the firewall through the 2nd wire. if i jump the plug end @ the switch end the brake lights come on.if i plug the switch in with it not screwed into the trans the back up lights come on. I looked in the trans with the switch out and it seems to be in the correct position, What is my problem?