Under Seat Fuse Box. How to Unlock??? [Archive] - Chevy Jul 11, 2016How in the blibbity bleep do you access (unlock) the underseat fuse panel in the EXT(assuming st is same type box) under the second row seat. I consider myself above average on the mech. inclined scale but these little unlock tabs have got me stumped. GMC Envoy (2002) - fuse box diagram - Auto Genius Dec 11, 2016GMC Envoy (2002) – fuse box diagram. Year of production: 2002. Engine Compartment Fuse Block GMC Envoy mk2 – fuse box – engine compartment. The fuse block is located under the hood in the engine compartment on the driver’s side of the vehicle.