I bought an 02 rendezvous the other day ran great, next day no start just cranks... ive narrowed it down to i thin it has a passkey issue, the column was taken apart when i bought it, i checked fuel, spark, and compression, runs on starter fluid... everything says if passkey is the issue ill have a security light on the dash on... have seen it on the screen one time while cranking but never again...

additionally, when i go outside every morning car will start and run for a couple seconds then dies and does nothing but crank... what do i need to do or check.... im very mechanically inclined

 

you may want to check the crank sensor some of thewse buicks will have a bad oil plug slinging oil all over the motor and possible the crank sensor