The passenger side brake light goes out intermittently. I switch the existing brake light bulbs and the problem remains. The "brake" dash light is off. I checked all of the fuses and they are good. The "check engine" light is on but I think this is unrelated. It must be electrical. I don't want to take it to a mechanic but I don't know how to start to diagnose the problem. Could you please suggest a starting point?