backup lights oddity

[hplacecf]

backup lights issue.

1977 Chevrolet c10 stepside.

bought used, so I don't now the history.

the backup lights never worked since I got the truck. it was something I was going to get around to in the restoration process. I just thought some fuse was blown or something.

today, the backup lights were on while I was driving away from my house - wife saw them and told me when I got back.

so, I guess it is not a fuse since they came on, but they should not come on when I am driving. I tried recreating the situation, but couldn't.

what should I look at to figure out how to get them to work correctly, now that I know that they do work (if not correctly).

thanks