One problem related to tail light switch has been reported for the 2009 GMC Terrain. The most recently reported issues are listed below.
The contact owns a 2008 GMC Terrain (n/a). The contact stated that when using the automatic option for the headlights, he assumed that the tail lights would also illuminate. The tail lights would automatically during daytime hours when there was low visibility, such as fog or snow. The manufacturer was not contacted and there were no repairs made to the vehicle. The VIN and failure mileage was unavailable.