2004 Pontiac Grand Prix GT

I've had a ton of experience with this car and the databus antitheft bypasses. I've tried the dbpass 23, pldata, pkg 4 and 5 to no avail. I ended up back where i started using the equivalant of a 556u and you need to hook up keysense wire to it to prevent it from seeing two transponders at the same time or you will get a service theft system message in info center. sound familiar? also, using the databus bypasses, of the ones that worked, they all would intermittently cause miscommunication in data lines during remote start and shut down the instrument panel (no rpm, gas gauge, trac lite off) and low fuel message. I used the ultrastart 1250 and with this unit you can retain driver priority unlock feature by using the rearm and disarm outputs for factory alarm to trigger lock and unlock.  grand prix is goofy too when you disarm alarm it automatically unlocks driver door. 1250 has automatic rearm after start option in programming, too. a litte hairy, but do a few and they're fine. good luck!

I would definitely recommend using the key style bypass with a keysense shut off (556u by dei) because if it starts with one key and either sees another key at the same time or sees both gone after starting, it will trip that code. I believe it will reset itself after x amount of successful cycles, but I was installing it at the dealer and had a tech 2 to reset the code. this way you don't run into any of the traction control crap. gimme a shout if you have any more q's