Isn't much to these selector valves. Often they quit working cause they're to dirty to work.


Removing, and cleaning it might get it working again, or the fuse for it is burned.


Heres what it looks like, yours might be slightly different, as this one is on my 1985 E350 Diesel van.







Personally, I wouldn't bother with it, if the rear tank works, just use that one.