One problem related to tail light switch has been reported for the 2006 GMC Envoy. The most recently reported issues are listed below.
The contact owns a 2006 GMC Envoy. While turning, the left turn signal on the instrument panel blinked and then began to blink very fast without warning. When the left turn signal was engaged, the tail light failed. The failure recurred each time the left turn signal was engaged. The vehicle was not taken to the dealer or repaired. The manufacturer was made aware of the failure. The approximate failure mileage was 140,000.