I have a 91 Toyota Corolla DX, at night when I have my lights on, I have all lights. When I hit my brakes, my right side brake light goes out. We have cleaned all connections, checked electrical wiring and made sure grounding was good and also replaced all bulbs whether they were burnt or not. What else could be the problem ???

There are 3 possibilities that come to mind (there may be more) 1. is you have fitted the wrong type of bulb i.e. single contact single filament in a double contact double filament socket or even a double contact single filament, anyway check that first. 2. It could be a short either in the wiring possibly in the boot or number plate light (wherever it can get chaffed or somthing heavy dropped on it 3. its a bad earth. personally I would go for option 1. I've seen it a hundred times, you can allways check this by looking at the number of contacts when you remove the bulb (just check that one of the contacts is not shorting out on the side of the unit). bulbs might look the same but aren't