If you look at the schematic, the following apply:
If you measure the Ignition Relay and have 12V at 14 (which comes from 10 at the Circuit Breaker), AND 12V at 11 coming from the Fuse Box, then you'll automatically have 12V at 15 unless the Ignition Relay is bad or you have a bad ground at the relay.
15 is the feed to all the swiches, so if you DON'T have 12V to 15 at any of the switches, but DO have 12V to 15 at the Ignition Relay itself, then you have a broken wire somewhere.
The Ignition Relay is located behind the kick panel on the drivers side of the car and all the wires run up under the dash or inside the channels under the door sill plates.
I suppose you could possibly have a bad motor causing the problem, but if a motor was bad (grounding out), then the circuit breaker would "break" and you "shouldn't" be getting 12V on the supply side going into the car.