I want to know how to program the clock on 2004 avalanche?

Hello, I service most Ford family of Brands. I can tell you that there is usually a button on the radio that has RDS printed on it. When this button is pressed, it will indicate the Hours column. Once the Hours column is adjusted, you press RDS again and it should toggle to the Minutes column. Then do the same thing as you did for the hours column to advance the numbers.

Some of the radios use the up and down selector button to move the numbers in the clock window. The numbers will either advance 1 number per push or scroll as long as the button is held down. When you are finished, some radios will automatically return to the normal position. Other radios need a push on the RDS button to return to normal.

Again, I service a different Brand of vehicle and your radio may not work this way, but there is no harm in trying to reset it.