Lexus ES 330 tail light out

If no lights are turned on and the indiator is showing, it could be a fault with the indicator control module.

If only when lights are turned on and none of the lights are burnt, it could be due to poor contacts with certain bulbs or some bulb used are out of specs.

Thanks KHLow2008. I jiggled the rear bulbs in their sockets, and voila! the indicator light went out. It is odd that it came on when no lights were turned on, though.
Dave

That indicates some bulbes or wiring connectors are loose and the lights could be intermittently not working.

When no lights are turned on, the control module needs a complete circuit to keep the indicators off and when you jiggled the wireharnesses/bulbs, the contact has been restored thus the light went off.