1994 BMW 318 Short in lights on passenger side.

Electrical problem
1994 BMW 318 4 cyl Two Wheel Drive Manual 300k miles

I have a short somewhere that affects my dash lights and passenger side lights in a weird way. My instrument lights and dash lights do not work even though the instrument panel does work. My passenger side lights don't come on when I turn on my headlights. My drivers side lights do come on, however, the brake lights doesn't work on either side at night or in the day. I have replaced all the bulbs and am stumped at what the problem could be. Please help me guys.

I bought the car two weeks ago. The lights were on when I test drove the car from the private owner. After I bought it that's when the lights acted up. I called the owner and he said that if I "played with the brake light switch it would come back on. I have no idea how to get to the brake light switch though.