Raider 4WD V6-3.7L SOHC (2007)
Keyless Entry Module: Description and Operation
MODULE - SENTRY KEY REMOTE ENTRY
DESCRIPTION
The Sentry Key REmote Entry Module (SKREEM) (1) is sometimes referred to as the Wireless Control Module (WCM). The SKREEM is the primary
component of the Sentry Key Immobilizer System (SKIS). It is also the receiver for the Remote Keyless Entry (RKE) system. The SKREEM is located
on the right side of the steering column, near the ignition lock cylinder housing and is concealed beneath the steering column shrouds. The molded black
plastic housing for the SKREEM has an integral molded plastic halolike antenna ring (4) that extends from the bottom. When the SKREEM is properly
installed on the steering column, the antenna ring is oriented around the circumference of the ignition lock cylinder housing.
A single integral connector receptacle (3) is located just behind the antenna ring on the bottom of the SKREEM housing. An integral molded plastic
mounting tab (2) on the rear corner of the SKREEM housing has a hole in the center through which a screw passes to secure the unit to the steering
column. The SKREEM is connected to the vehicle electrical system through a single take out and connector of the instrument panel wire harness.
Several unique SKREEM modules are used: one for vehicles equipped with RKE only, one for vehicles equipped with RKE and SKIS, and another
version has an additional coaxial connector receptacle that allows it to receive inputs from the optional remote start antenna module. The SKREEM
cannot be adjusted or repaired. If ineffective or damaged, the entire SKREEM unit must be replaced.
OPERATION
The Sentry Key REmote Entry Module (SKREEM) (also known as the Wireless Control Module/WCM) contains a Radio Frequency (RF) transceiver
and a microprocessor. The SKREEM transmits RF signals to, and receives RF signals from the Sentry Key transponder through a tuned antenna enclosed
within the molded plastic antenna ring integral to the SKREEM housing. If this antenna ring is not mounted properly around the ignition lock cylinder
housing, communication problems between the SKREEM and the transponder may arise. These communication problems will result in Sentry Key
transponder-related faults.
The SKREEM also serves as the Remote Keyless Entry (RKE) RF receiver and may receive RF inputs either directly through an internal antenna from
the RKE key fob transmitter or, on vehicles equipped with an optional remote start system, indirectly through the external remote start antenna module.
The SKREEM communicates over the Controller Area Network (CAN) data bus with the Electromechanical Instrument Cluster (EMIC) (also known as
the Cab Compartment Node/CCN), the Powertrain Control Module (PCM), or the diagnostic scan tool. The SKREEM and the PCM both use software
that includes a rolling code algorithm strategy, which helps to reduce the possibility of unauthorized Sentry Key Immobilizer System (SKIS) disarming.
The rolling code algorithm ensures security by preventing an override of the SKIS through the unauthorized substitution of the SKREEM or the PCM.
However, the use of this strategy also means that replacement of either the SKREEM or the PCM units will require a system initialization procedure to
restore system operation.
The SKREEM retains in memory the ID numbers of any Sentry Key transponder that is programmed into it. A maximum of eight Sentry Key
transponders can be programmed into the SKREEM. For added system security, each SKREEM is programmed with a unique Secret Key code. This
code is stored in memory, sent over the CAN data bus to the PCM, and is encoded to the transponder of every Sentry Key that is programmed into the
SKREEM. Therefore, the Secret Key code is a common element that is found in every component of the SKIS.
