When i turn the lights on headlamps, the bulb failure light comes on. I have checked every light and have found this: The right rear tail light will not burn. When I step on the brake it lights up though. The left (driver) side tail light is burning. I tested w/ voltmeter and there is no current going to the right side. The both brake lights work when the brake is depressed. The flashers and backup lights work fine on both sides but the doggone right rear one will not burn when the headlamps are on unless the brake pedal is pushed. Could this be a bulb relay failure causing this, or is it something else? Help