Toyota Repair: Fuse Blows out for brake lights, toyota 4 runner, dash lights

Question
Hi,
I have a 1996 Toyota 4 Runner, for some unknown reason the fuse keeps blowing causing the brake lights and dash lights not to work. We have changed the tail relay and tail fuses. The just keep blowing out. Can you help me with this. Also the steering wheel shakes really bad especially at high speeds, could this be the brakes, struts or shocks? Your help will be greatly appreciated.

Answer
Does it have a trailer hitch and is it an aftermarket installation or the factory installed unit, the most common problem is that there is a problem with the trailer wiring so let me know and I can help more.
If the steering wheel shakes at higher speeds without touching the brake pedal have the tires balanced.