Is this your brake, blinker or back up light? And if it remains illuminated even with the key out, then there's a short in switch/wiring controlling that circuit. This would be located (in the circuit) on the side feeding power to the fuse and not the side feeding power to the bulb.
You need to remove the switch controlling the circuit and use a test light/volt meter to probe the circuit until you find the short.
Tuesday, February 1st, 2011 AT 11:46 AM