How to program your Chevrolet C/K 1500, C/K 2500, C/K 3500, 1997, 1998 and 1999 CK
First take a metal paper clip and make it into a “U” shape.
Then find your Data Link Connector (DLC). This is under the dash and steering column where you test your computer.
There is two rows of 6 slots. They are lettered like this:
“F E D C B A” (TOP ROW)
“G H J K L M” (BOTTOM ROW)
 Connect slot “A” and slot “G” of the data link connector (DLC), with the metal paper clip.
In other words, counting from left to right, on top row, put one end of the metal paper clip
in slot 6, then counting left to right, on second row, put the other end of the metal paper
clip in slot 1 of the DLC.. The vehicle responds with door locks locking and unlocking.
 On the first remote, hold down the Lock and Unlock buttons simultaneously until vehicle
responds with locks locking and unlocking, horn beeps. (this could take up to 20 seconds
for each transmitter).
 Do this for up to 4 transmitters. Then disconnect the paper clip from the DLC.
 Note: The ignition switch being on or off, during programming, enables or
disables the horn beep feature when lock on transmitter is pressed twice within
5 seconds period.