Looking at the electrical drawings in the service manual since your horn and tail light work I don't think the problem is a fuse. Both the drawings for the 1600 and 1700 show horn, tail lights, speedometer, and brake light to be on the same fuse, called signal light fuse. I think all your fuses are in the left side or under the seat. They don't show any others on the drawings.
Are you able to get to a connection at the light? You need to know if you have power there. If not then go the switch's and check it there. There should always have power on one side of the switch. Voltage should appear on the other side of the switch when you push the brake that switch is for.
If you have power at the light check the grounds. Pay attention to the connectors. Sometimes a wire will brake right where it goes into the connector. I would say if you have power at the light and also a good ground the light is bad. You might take the seats off when tracing the wires.
I believe the power lead to the switches are brown, the lead to the light is yellow. If I read the drawing color code right.
Last edited by linerdave; 03-26-2011 at 06:07 PM.