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It is most likely a fault in the security system, which will require being diagnosed with a gm factory level scanner. But before you have that done, try the gm security reset/relearn procedure. If problem occurs again after this is done, then you will need to have it professionally diagnosed with the gm level scanner.
Ok, what we are going to try is a re-learn procedure, but you will need your original master key for this, it cant be a duplicate.
Important: The vehicle learns the key transponder information and/or passwords on the ignition switch transition from OFF to RUN. You must turn the ignition OFF before attempting to start the vehicle.
ok, we definitely have a hard fault or problem in the antitheft system and will need to be hooked up to a scanner for this