Chrysler Voyager Forum : “valet code - central door lockingsystem doesn't works”

valet code - central door lockingsystem doesn't works

Sometimes our Voyager (2.4 SE deluxe 2001) switched automatically into the valet code. The central locking doesn't works and we can't start the car. After we open manually the door, we often hear a clicking sound, it finally succeeds when we enter the secret valet code (two-button switch mounted on the console) and finally we can start the car. Who knows what makes the car automatically into the valet code and what making the ticking sound and how to solve?  
Our car is fitted with a Clifford Concept 300 system.  Hope someone can tell us more about this problem...