2004 Chevrolet Express Van Owner's Manual - Page 164

Setting the Time for Radios without Radio Data Systems (RDS) Press and hold the HR or MIN arrow for two seconds. Then press HR until the correct hour appears on the display. Press and hold MIN until the correct minute appears on the display. The time may be set with the ignition on or off. Setting the Time for Radios with Radio Data Systems (RDS) Your radio may have a button marked with an H or HR to represent hours and an M or MN to represent minutes. Press and hold the hour button until the correct hour appears on the display. Press and hold the minute button until the correct minute appears on the display. The time may 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 RDS TIME appears on the display. To accept this time, press and hold the hour and minute buttons, at the same time, for another 2 seconds. If the time is not available from the station, NO UPDAT will appear on the display. RDS time is broadcast once a minute. Once you have tuned to an RDS broadcast station, it may take a few minutes for your time to update. 3-44