U.S. safety regulators are investigating thousands of Volkswagen SUVs because the outside lights can go out unexpectedly.

The probe affects 61,000 VW Tiguans from the 2009 through 2011 model years.

The National Highway Traffic Safety Administration says 26 drivers have complained about headlights, tail lights and turn signals going dark. Many said they found an overheated and melted fuse under the hood. The agency says the fuse controls several exterior light circuits. The complaints say the problem gets worse over time.

A VW spokesman says he's checking into the matter.

The problem hasn't caused any crashes or injuries. Investigators will determine if it's bad enough to cause a recall.