7 way plug inside 72 ambassador

[Ryocomjr]

Hopefully I'm asking in the right area. I've searched and unless I'm not saying it right I'm not coming up with much. We have a 72 ambassador 29' and the brakes do not work. Originally when we got it they would lock up with just a 7 pin plug with no controller. I unhooked the white wire from the inside of the A/S I now have a new truck with controller and can't for the life of me remember where the white wire goes. Can anyone help?

[Dingo Girl]

My 67 the white was the ground.