WHY DOES MY SECURITY LIGHT FLASHES AND IT WANT CRANK WHEN FLASHING on 2003 GMC Envoy

IT CRANKS WHEN ITS NOT FLASHING BUT WHEN IT FLASHES IT WANT DO NOTHING

3 answers
there maybe a problem with the onboard security system...
Do you use the same key every time?
scan anti theft for codes and post so we can adv