1988 IDI No brake lights. Fuse good. Where do I start? There are two switches on brake pedal. Which is the switch for brake lights? I have turn signals.

 

one of the switches is for brake lights, the other is for cruise control shut off.
the brake light switch should have one side always hot.

 

I have no brake lights. There is no hot wire going to brake light switch. The turn signals work. What do it look for next?

 

How do you know the fuse is good? Did you try swapping it for another? (just double checking what you did, because sometimes they look good, but aren't).

IIRC, cruise brake switch would be vacuum on an 88, so start at the brake switch with wires, and try to trace which wire goes back to the fuse panel. Like Tom said, one of those wires should be hot at all times, if neither one is, it sounds like your problem is there.
If both switches have wires, then you'll have to trace both until you find where the problem is.

 

Does the hot wire to the brake switch go directly back to the fuse? Also does the turn signal switch have any thing to do with the brake lights?

 

https://www.ford-trucks.com/forums/1...t-problem.html
This thread has wiring diagrams that should answer your questions. It may not be exactly the same as your 88 but close enough.

 

brake light fuse is top left, above the turn signal flasher, 15 amp. top right 15 amp fuse is tail light/parking lights