GM Service Manual Online
For 1990-2009 cars only

The radio might have a button marked with an H or HR to represent hours and an M or MIN to represent minutes.

Press and hold the hour button until the correct hour displays. AM appears for morning hours. Press and hold the minute button until the correct minute displays. The time can be set with the ignition on or off.

To synchronize the time with an FM station broadcasting Radio Data System (RDS) information, press and hold the hour and minute buttons at the same time until UPDATED displays. If the time is not available from the station, NO UPDATE displays.

RDS time is broadcast once a minute. After tuning to an RDS broadcast station, it could take a few minutes for the time to update.