2000 Mercedes Benz S430 • V8 2WD Automatic • 150,000 miles

The left lower rear outboard tail light remains illuminated and does not go off without pulling the plug. Reinstalling the plug just re-illuminates it. It stays on key on/off and out.
What to do to fix?
Thank you.
January 30, 2011.

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.

Ernest Clark
Feb 1, 2011.
Check that the light switch is turned off as these will have a L & R night parker that will stay on, check your owners manual and if the switch is in the full off position have a mechanic check the switch for a fault.

Mark (mhpautos)

Feb 4, 2011.