Transmitter Synchronization

WARNING: This page is about a different car, the 2003 Pontiac Aztek and 2003 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.

Resynchronization may be necessary due to the security method used by the remote keyless entry system.
The transmitter does not send the same signal twice to the remote control door lock receiver (RCDLR).
The RCDLR will not respond to a signal that has been sent previously.
This prevents anyone from recording and playing back the signal from the transmitter.
Resynchronization may be necessary under the following conditions:
1. The battery in the transmitter is very weak.
2. The battery in the transmitter was replaced.
3. The battery in the vehicle has been in a low or no charge condition for an extended period of time.
In order to resynchronize the transmitter with the RCDLR, perform the following steps:
1. Stand within 1.5 m (5 ft) from the vehicle.
2. Simultaneously press and hold the LOCK and UNLOCK buttons on the transmitter for 7 seconds.
  The horn should chirp in order to confirm synchronization.