1997 GMC Safari Owner's Manual - Page 84

Synchronization Synchronization may be necessary due to the security method used by this system. Thetransmitter does not send the same signal twice to the receiver. The receiver will not respond to a signal it has been sent previously. This will prevent anyone from recording and playing back the signal from the transmitter. Sliding Door To resynchronize your transmitter, stand close toyour vehicle and simultaneously press and hold the LOCK and UNLOCK buttons on the transmitter for eight seconds. The door locks should cycle toconfirm synchronization. If the locks do not cycle, seeyour dealer forservice. To open the sliding side door, pull the handle toward the back and slide the door to the rear until it rests in the open detent position. To close the sliding side door, you must first pull the door past the open detent position.