First off the radio interface modules for the 04+ grand prixs DO NOT WORK PROPERLY.
they will for sure 100% cause data communication errors.
Pull that **** out and just hook the red accessory off the aftermarket radio to the wiper fuse (easiest access for a rap circuit to turn the radio on) or any accessory/ignition wire.
Without the module you will lose chime, onstar and the date in your dic that's it. This is assuming you don't have monsoon, os04 is required for monsoon and the os01 will not work properly
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