Keyless Entry: Description and Operation
REMOTE KEYLESS ENTRY SYSTEMTwo different Remote Keyless Entry (RKE) systems are offered as optional factory-installed equipment on this model. Both RKE systems are offered only on models that are also equipped with power locks. On vehicles that are not equipped with the optional Vehicle Theft Security System (VTSS), the RKE system control components are integral to a power lock and Remote Keyless Entry (RKE) module. Vehicles that are equipped with the VTSS option have their RKE system control components integral to a microprocessor-based Central Timer Module (CTM). Both RKE systems are radio frequency systems that allow the use of a remote battery-powered radio transmitter to control the power lock system.
The CTM is compatible with a two button TRW RKE transmitter (keyfob). Two pre-programmed transmitters will be supplied with each vehicle. The CTM is capable of retaining up to four transmitters which can be programmed using the DRBIII or by the customer. When a signal encoded with the correct vehicle access code is received and contains a valid message, the CTM will activate the corresponding relay to lock or unlock the doors. When an unlock message is sent, all the doors will unlock, the VTSS will disarm and the illuminated entry will be activated. When a lock message is sent and all the doors are closed, all the doors will lock, the VTSS arming sequence will begin and the illuminated entry will turn OFF.
Both RKE Systems include an illuminated entry feature, which turns ON the courtesy lamps for a timed interval (about thirty seconds), when the power door locks are unlocked using the RKE transmitter. However, the CTM-based RKE system offers additional features that are not available with the power lock and RKE module-based system.
The only physical difference between the two RKE systems lies in the location of the system control circuitry and logic, the RKE receiver, and the illuminated entry system relay. Each RKE system includes the RKE transmitters and one of the following modules, which are described in further detail elsewhere in this service information:
Central Timer Module - A Central Timer Module (CTM) is used on this vehicle when it is equipped with the optional Vehicle Theft Security System (VTSS). The CTM is concealed under the instrument panel, where it is secured with three screws to the inboard side of the left center instrument panel support above the engine housing. The CTM provides the proper RKE system features based upon the monitored inputs. The CTM circuitry monitors Radio Frequency (RF) inputs from the RKE transmitters, hard wired switch inputs, as well as message inputs received from other vehicle electronic modules on the Chrysler Collision Detection (CCD) data bus network.
Body Control Module
Information Bus
Power Lock and Remote Keyless Entry Module - A power lock and Remote Keyless Entry (RKE) module is used on vehicles that are not equipped with the optional Vehicle Theft Security System (VTSS). The power lock and RKE module is concealed under the instrument panel, where it is secured with two screws to the inboard side of the left center instrument panel support above the engine housing. The power lock and RKE module contains integrated circuitry and programming that allow it to provide the proper RKE system features based upon Radio Frequency (RF) inputs from the RKE transmitters, and numerous hard wired inputs.
Keyless Entry Transmitter - The keyless entry transmitter is a small, battery-powered, RF transmitter that is contained within a molded plastic case that is designed to also serve as a convenient key fob.
Some of the additional features of the RKE system found in vehicles with the VTSS option include:
Horn Chirp - The CTM provides an optional horn chirp feature. This is a programmable feature.
Vehicle Theft Security System Control - The RKE transmitter also arms and disarms the factory-installed vehicle theft alarm.
Hard wired circuitry connects the RKE system components to the electrical system of the vehicle. These hard wired circuits are integral to several wire harnesses, which are routed throughout the vehicle and retained by many different methods. These circuits may be connected to each other, to the vehicle electrical system and to the RKE and power lock system components through the use of a combination of soldered splices, splice block connectors, and many different types of wire harness terminal connectors and insulators. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, further details on wire harness routing and retention, as well as pin-out and location views for the various wire harness connectors, splices and grounds.
Many of the electronic features in the vehicle controlled or supported by the CTM are programmable using the DRB III scan tool. In addition, the CTM software is Flash compatible, which means it can be reprogrammed using Flash reprogramming procedures. However, if any of the hardware components of the power lock and RKE module or of the CTM are damaged or faulty, the entire module must be replaced.
Both versions of the Remote Keyless Entry (RKE) system allow the power lock system to be operated remotely using the RKE transmitter. Both versions will also provide an illuminated entry feature, which uses a hard wired output to turn ON the interior lighting for a timed interval (about thirty seconds) when a valid Unlock message is received from the RKE transmitter. On vehicles that are equipped with the optional Vehicle Theft Security System (VTSS), the RKE transmitter also arms and disarms the factory-installed Vehicle Theft Security System (VTSS). Two small, recessed buttons on the outside of the transmitter case labelled Lock, and Unlock allow the user to choose the function that is desired. The RKE transmitter then sends the appropriate Radio Frequency (RF) signal. An RF receiver that is integral to the power lock and RKE module or the Central Timer Module (CTM) receives the transmitted signal, then uses its internal electronic programming to determine whether the received signal is valid and what function has been requested. If the signal is valid, the module then provides the programmed outputs to produce the system features.
On vehicles that are equipped with the optional Vehicle Theft Security System (VTSS), the RKE system also provides a programmable horn chirp. If this feature is enabled, when a valid Lock message is received from the RKE transmitter, the CTM provides an audible confirmation by momentarily pulling the control coil of the horn relay to ground through a hard wired circuit output.
The RKE system operates on battery current received through a fused B(+) circuit from a fuse in the fuse block so that the system remains functional, regardless of the ignition switch position. The power lock and RKE module can retain the vehicle access codes of two RKE transmitters. The CTM can retain the vehicle access codes of up to four RKE transmitters. In both versions of the RKE system the transmitter codes are retained in RKE system memory even if the battery is disconnected. If an RKE transmitter is faulty or is lost, new transmitter vehicle access codes can be programmed into the system. The hard wired inputs or outputs of the RKE system can be diagnosed using conventional diagnostic tools and methods; however, for diagnosis of the CTM or the CCD data bus, the use of a DRB III scan tool is required. Refer to the appropriate diagnostic information.