Brakes lock up in reverse!!??

[bkrome]

Hi, I have seen a couple of discussions which touch on parts of my dilema, but I still need some help. I aquired a down and out 1968 22' Safari recently. Before I pulled it very far I had my local rv shop peek at the running gear to give me some clarity. They said original breaks had life left, and were functional with the replacement of the pigtail. Now all the lights function as they are supposed to, with the exception of the back-up lights. And when driving I can push the button on my break controller and feel the trailer brakes lock equally. However, when I put the sucker in reverse, it is totally locked up. If I unplug the pigtail from the TV, no problem backing up. I am worried I have no breakes forward however. I speculate that the tech wired the aux/back-up to the yellow break cable, but why then can I manually toggle from the controller? Weird, if anyone can shed light on this I'd be much appreciative. Thanks Krome