FYI
just to help out any one else with a 2006 impala v6 that suddenly won't crank or start, the air box intake on the fresh air side is a perfect hide-e-hole for rodents and has an ample supply of wiring to keep them busy and a heat sink to keep them warm. A rat eat through 42 wires on ours resulting in a $900 repair bill. screening on the air intake horn could have prevented this if it had been known that there was wiring in the air box . It has been an unseasonally cold winter and rodents like this warm rat cave. The initial diagnosis was bad security module or bad starter, NOT rodent damage the car was only sitting for 1 day