Keyless Entry: Description and Operation

Fig. 1 Remote Keyless Entry (RKE) Transmitter:

REMOTE KEYLESS ENTRY
The Viper utilizes an Entry Module. The Entry Module provides Remote Keyless Entry (RKE) functions as well as opening or unlatching of the doors. The RKE system allows locking and unlocking as well as arming and disarming of the security system with a hand held radio frequency transmitter. The transmitter sends out a rolling code for high vehicle security. The transmitter has two buttons for operation. They are LOCK and UNLOCK.

The UNLOCK button will unlock both the drivers and passenger side doors. Upon pressing the LOCK button, the horn will sound a short CHIRP to notify that the all door lock signal was received. The driver and passenger lock switches are wired in parallel and form one input to the entry module. When the entry module receives a lock input, both doors are locked. When an unlock signal is input to the entry module, both doors are unlocked and the park/tail lamps are flashed ON and OFF twice. If the key is ON, and an inside door handle input is seen and vehicle speed is below 8 to 13 Km/h (5 to 8 mph), both doors will be unlocked. The lock switch is a momentary contact type switch and either door will lock or unlock the entire vehicle. The key fobs are unique to the Viper and utilize a rolling code system. The rolling code feature changes the key fob message each time it is used. The key fob message and the receiver message increment together. Under certain conditions with a rolling code system, the receiver and transmitter can fall out of synchronization. The system will accept up to four fob codes.