odd wire in cab

[llong66]

I have an 85 1008 and I have a wire I cant figure out, it runs from up under the center of the dash, down the tunnel through the hole for the 4wd selector, under the truck it runs to a connector on the top rear of the tranny. Is the the rev light switch, or the 4wd indicator light? I am wondering why it is routed this way, I have not noticed anything like it in other ppls pics.

 

[Warthog]

4wd switch. The backup light switch is on the steering column