This page was created to help out all those folks with 1995 and later GM trucks that refuse to pay $50 or more for a mechanic to do 30 seconds worth of labor. The procedures documented here should work for the models listed, and may work for others with a similar computer setup.
For all model years, you can program up to 4 key fobs for a single vehicle. However, in order for all of your fobs to work, they have to be programmed at the same time. This means that if you've purchased a third fob, you'll have to reprogram the first two again when you program the new one.
The reason for this is that you're not really programming the fob itself. During the programming process, you're actually putting the truck into 'learning' mode, and telling it 'here are the fobs that you may accept'. It erases all previous memory of any old fobs, so they all have to be reprogrammed. From a security standpoint, this is good design, as it gives you a way to nullify a stolen fob.
The procedures are different for the old body style and new body style trucks. Old body style for Tahoe/Yukon and Subs is 1995 through 1999, new body style is 2000 and up. For pickups, the old body style goes through 1998, and the new body style starts in 1999. Note that there were some leftover old body vehicles that were 'gussied up' and sold in the new body years, so go by what you know you have. NOTE: When I refer to trucks, I'm referring to pickups, Tahoes, Yukons, and Subs as a whole.
1) Close all the vehicle doors.
2) Insert the ignition key into the ignition lock cylinder.
3) Press and hold the door unlock switch.
4) While holding the door lock switch in the unlock position, cycle the ignition ON, OFF, ON, OFF.
5) Release the door unlock switch. The doors will lock and unlock to confirm the program mode.
6) Press and hold the LOCK button and the UNLOCK button simultaneously on one transmitter. After a delay of approximately 15 seconds, the doors will lock and unlock to confirm the programming of that transmitter.
7) Repeat the previous step to program up to four transmitters.
8) Turn the igntion switch to the RUN position in order to exit the keyless entry transmitter mode.
9) Operate the transmitter functions in order to verify correct system operation.
The OBDII Data Link Connector (DLC) is located under the dashboard near the steering wheel shaft. The
image below is rotated 90 degrees to the left (left is 'up'). Use a paper clip bent into
a 'U' to ground the pins as instructed.
1.Ground pin 4 to pin 8 of the data link connector (DLC). The receiver will respond by locking and unlocking
the doors, and activating the liftgate window release (if equipped) within 2 seconds.
2.Press and hold the LOCK and UNLOCK buttons simultaneously on the first transmitter to be programmed until the locks cycle (approximately 10 seconds).
3.Repeat step 2 for up to four total transmitters to be programmed (if available). The receiver will respond by locking and unlocking the doors and activating the liftgate window release (if equipped) within 2 seconds.
4.Remove the ground applied to the DLC.
5.Lock and unlock the doors in order to verify the transmitter operation.
6.Activate the rear window release in order to verify the transmitter operation.