Toyota Repair: 1992 Toyota Corolla DX wagon with brake light issue

Question
Greetings
So here is the problem, at night my brake lights are on like I'm about to stop, though I am not stopping. It is apparently clear that this is tied to my parking/head lights being turned on. Once these are off, it works normal. So what would be the cause?

Answer
Check all the bulbs in the rear, make sure the bulbs installed are the correct type and match the number of contacts in the sockets, look for any burned or shorted wires. somehow voltage is being applied through light circuit to the brake lights, it could also be the turn signal switch (combination switch) on the steering column.
By any chance is there a trailer hitch on it?