Remote Control Transmitter programming for Chevrolet Astro (1998-1999) is very simple.
First - you must find Data Link Plug (Diagnostic Connector, OBD2 Plug) in your vehicle and follow the instructions below.
☛ Obtain all remote transmitters for this vehicle. This procedure will erase all previously programmed remotes.
You must program all existing and new remotes that you wish to use on the vehicle at this time.
1. Locate the Data Link Connector. It is located under dash drivers side.
2. Connect pin 8 to pin 4 with a suitable jumper wire.
Any short piece of conductive wire will work (i.e. – a paper clip).
You will leave the jumper wire connected throughout the programming procedure.
At this moment, the vehicle will should respond by locking and unlocking the doors to indicate that the vehicle entered programming mode.
If the vehicle will NOT respond (by locking and unlocking the doors to indicate programming mode) - Insert key into the ignition and turn the ignition cylinder to the ON position (don't start the car).
3. Press and hold both the LOCK and UNLOCK buttons together on the first transmitter to be programmed.
4. After about 15 seconds, after the vehicle will respond by locking and unlocking the doors, release the buttons on the transmitter.
5. Within one minute, repeat Step 3 on all additional remotes (including working ones).
6. Remove the jumper wire connected to the Data Link Port. Programming is now complete.