Please help mkIII weird problems
 

So I got a 1990 mkIII and when I turn the car on everything starts up besides the entire dash is out everything gauge wise windows are out too until I hit the brake pedal then everything turns on even the ding I think he car then I let go of the pedal and it all turns off. I’m blowinf the 7.5 fuse to the gauges every time I hit the brake. Now if I don’t start it and hit the brake everything starts working again without the key in which is weird can someone point me in the right direction

Got to be a short somewhere. If you take out the brake light fuse do you get the same results?
Also look for wires around the brake pedal under the dash. Maybe hitting something there? Moving a wiring harness?

Just as a shot in the dark, try unplugging the brake light failure module which is located near the rear hatch latch behind the plastic cover that goes from one side to the other. The module on the drivers side. Water tends to get into it and cause problems. I fixed mine and put it inside a plastic bag so water couldn't get in again. Check your ground wires for the battery and the bundle of harness wires that attaches under the intake manifold. I left it hand tight once and it acted weird until i tightened it down.