If no power to lamps then as stated check "all" stop lamp fuses. There is a 25 amp ST/LP fuse#12 in the underhood fuse block and it is before the brake switch. After the switch there is a 10 amp VEH CHMSL fuse#16 (high mount stop lamp) and a 15 amp VEH STOP fuse#34 in the rear fuse block (under left middle seat). It's not uncommon for the high mount lamp to go bad internally. If fuses are good then check the stop lamp switch. Switch is mounted on brake pedal. Orange wire is power in from the ST/LP fuse and should be hot with key on or off. The white wire is power out when pedal is pressed and goes to the CHMSL and STOP fuses then to the lamps. Also there is a recall for the circuit boards and bulbs out for that vehicle. It was released a long time ago so most likely it has already been done.
Hope this helps!
thanks, we have checked the switch and all the fuses. I know one of the boards has been replaced.