Reverse lights stuck on any time the key is on
 

1991 n/a rx7
I know i have seen other discussions about the reverse lights on these cars, but they all seem to be the opposite problem of what i am having. Any time my key is on, the reverse lights are stuck on. Could this be in the switch? Is there any other control circuits for the reverse lights other than the reverse switch on the transmission? Any help on where to start with this issue would be great.

Most likely cause is the back-up light switch. You're right in that the switch usually fails causing the back-up lights not to work due to high resistance, but nonetheless these switches frequently fail. Recommend replacing switch and washer as a first step. I've attached page from the Mazda wiring diagram.