Hi. Having an issue with my '92 Ford F700 that has air brakes. When I hit the brakes the brake lights dont come on. The bulbs are fine, the wires are fine. The brake lights work with the trailer control but not the pedal.
So I think it's the Stop Light Switch.The problem is I cant figure out there its located? Couldnt find any type of diagram or photos online. Is anyone familiar with this issue? Any help would be appreciated.

 

I'm pretty sure there are two separate switches for the stop lites. One for the footbrake and one for the trolly valve. Some were hidden under the dash . You will have to trace the lines from the footvalve and some were even mounted on the footvalve itself.

 

Thanks. And if you know where I can find any diagrams or pictures of the area online or anything or if you have a link, that'd be great.

 

See if these help..

 

Some systems had a combination valve that also functioned as a stop lite switch. Your best bet is to trace the green air lines(primary system) all the way to where they exit the cab. A clue is to look for any valve / switch with two terminals where one is the 12 volt supply and the other terminal goes to the stop lites.
You can prove out the circuit with a jumper across the two terminals and see if the stop lights come on.

 

Thanks everyone. The pics and explanation really helped. Now I get to go hopefully finally get it figured out. My boss will be happy.
Thanks again!