Keyless Entry: Description and Operation

INTRODUCTION
The Viper utilizes a new Electronic Entry Module (EEM). The EEM 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.

Transmitter:

SYSTEM OPERATION
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 EEM. When the EEM receives a lock input, both doors are locked. When an unlock signal is input to the EEM, both doors are unlocked. 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.

Resynch Activation Of The Transmitter
The Electronic Entry system has a rolling code for the RKE system. The transmitter and receiver increment together. If the transmitter buttons are pressed more than approximately 255 times out of range of the receiver, the transmitter and receiver are said to be out of synch. In this case the transmitter will no longer operate. The transmitter and receiver can be resynchronized by holding both the LOCK and UNLOCK buttons down for a period of 5 +/- 0.5 seconds. The receiver shall acknowledge a successful synchronization by commanding a horn chirp. Normal transmitter function will return.

CIRCUIT OPERATION
Key-In Switch Sense
Circuit G26 is connected to the Remote Keyless Entry (RKE) module and the key-in switch. The G26 circuit has switch located in the steering column that is normally OPEN with the key removed from the ignition. When the key is in the ignition the switch CLOSES completing a path to ground on circuit Z1.

When the system is ARMED and the RKE module receives an input that the ignition switch is being tampered with is activates the VTSS system.

Electronic Entry System
The Electronic Entry System (EES) performs three (3) functions. These functions are: Electronic Locking, Remote Keyless Entry (RKE), and Vehicle Theft Security System (VTSS).

The RKE module is the control for the system. Power for the RKE module is supplied from four sources. Circuit F33 is a direct battery feed. This circuit is protected by a 15 amp fuse located in cavity 5 of the Power Distribution Center (PDC). Circuit F35 also provides a constant battery feed to the RKE module. This circuit is protected by a 10 amp fuse located in cavity 20 of the fuse block. Power for fuse 20 is supplied by circuit A5. This circuit originates in the PDC, and is protected by a 30 amp fuse located in cavity 13.

Power for the module is also supplied on circuit G5. This circuit is HOT in the START/RUN position and protected by a 5 amp fuse located in cavity 11 of the fuse block.

Circuit V6 supplies power to the RKE module when the ignition switch is in the ACCESSORY and RUN positions. This circuit is protected by a 15 amp fuse located in cavity 3 of the fuse block.

Ground for the RKE module is supplied on circuit Z20. This circuit connects to three different cavities of the module.

To allow the module to communicate with the other modules in the vehicle the CCD Bus is used. The circuits involved are D1 for CCD (+), and D2 for CCD (-).