It looks like for the '99 model year you have to take it to the dealer and have them reflash the BCM. However try these steps for a 2000 model year, just in case it'll work:
MY 2000 (VIN Y)
1. Beginning with the ignition in OFF position, pull back on the turn signal/multifunction lever all the way toward you and hold it while you perform the next step.
2. Turn your key to ON and OFF twice. Then with the key in OFF position, release the turn signal/multifunction lever. Once you do this, you will hear the lock switch lock and unlock.
3. You are now ready to program the automatic door locks. Once you release the turn signal/multifunction lever you will have ten seconds to begin programming. If you exceed the ten second limit the locks will automatically lock and unlock to indicate that you have left the program mode. If this occurs, to continue programming your locks go back to step 1 above.
The following is a list of the available programming options:
^ All doors lock at 24 km/h (15 mph), only driver's door unlocks when key is removed: Press the LOCK side of the power lock switch on the door panel ONCE, and then the UNLOCK side ONCE.
^ All doors lock at 24 km/h (15 mph), all doors unlock when key is removed: Press the LOCK side of the power lock switch on the door panel ONCE, and then the UNLOCK side TWICE. (This is the factory setting)
^ All doors lock at 24 km/h (15 mph), none of the doors unlock when key is removed: Press the LOCK side of the power lock switch on the door panel ONCE, and then the UNLOCK side THREE TIMES.
^ No doors lock at 24 km/h (15 mph), none of the doors unlock when key is removed (Turns off automatic lock feature): Press the LOCK side of the power lock switch on the door panel TWICE.
You can exit the program mode any time by turning the ignition to ON. The locks will automatically lock and unlock to indicate you are leaving the program mode. If the lock/unlock switches are not pressed while in the programming mode, the respective auto lock/unlock setting will not be modified.
