You can program your 1997 GMC Sonoma remote yourself at home with these simple instructions.

Up to two remotes can be programmed (be sure to have both with you at time of programming)
Access the two red wired programming connector (located near the central locking module, behind LH lower instrumental panel)
Jump programming connector terminals
System should now lock and unlock doors to indicate programming mode actives
Proceed as follows:
*Press any button on remote transmitter once
*System should now lock and unlock doors indicating that the remote is programmed
Repeat last two steps for the second remote (if you have one)
Remove programming connector jump to exit programming mode