This is what it says in the manual for my 2009 T&C:
"Sound Horn with Remote Lock
This feature will cause the horn to chirp when the doors
are locked with the RKE transmitter. This feature can be
turned on or turned off. To change the current setting,
proceed as follows:
• For vehicles equipped with the EVIC, refer to “Sound
Horn with Lock,” under “Personal Settings
(Customer-Programmable Features),” under “Electronic
Vehicle Information Center (EVIC)” in Section 4.
• For vehicles not equipped with the EVIC, perform the
1. Perform this operation while standing outside the
2. Press the LOCK button on a programmed RKE transmitter
for at least 4 seconds, but no longer than 10 seconds.
Then, press the PANIC button while still holding
the LOCK button.
3. Release both buttons at the same time.
4. Test the feature while outside of the vehicle by pressing
the LOCK button on the RKE transmitter with the
ignition switch in the LOCK position and the key removed.
5. Repeat these steps if you want to return this feature to
its previous setting.
NOTE: Pressing the LOCK button on the RKE transmitter
while you are in the vehicle will activate the Vehicle
Security Alarm. Opening a door with the Vehicle Security
Alarm activated will cause the alarm to sound. Press the
UNLOCK button to deactivate the Vehicle Security