Description & Operation
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) and 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 halo-like 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.
Two SKREEM modules are used: one for vehicles equipped with RKE only, and one for vehicles equipped with RKE and SKIS. The SKREEM cannot be adjusted or repaired. If inoperative or damaged, the entire SKREEM unit must be replaced.
The Sentry Key Remote Entry Module (SKREEM) 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. The SKREEM communicates over the Controller Area Network (CAN) data
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 Sentry Key Immobilizer System (SKIS). Another security code, called a PIN, is used to gain access to the SKREEM Secured Access Mode. The Secured Access Mode is required during service to perform the SKIS initialization and Sentry Key transponder programming procedures. The SKREEM also stores the Vehicle Identification Number (VIN) in its memory, which it learns through a CAN data bus message from the PCM during SKIS initialization.
In the event that a SKREEM replacement is required, the Secret Key code can be transferred to the new SKREEM from the PCM using the diagnostic scan tool and the SKIS initialization procedure. Proper completion of the SKIS initialization will allow the existing Sentry Keys to be programmed into the new SKREEM so that new keys will not be required. In the event that the original Secret Key code cannot be recovered, SKREEM replacement will also require new Sentry Keys. The diagnostic scan tool will alert the technician during the SKIS initialization procedure if new Sentry Keys are required.
When the ignition switch is turned to the ON position, the SKREEM transmits an RF signal to the transponder in the ignition key. The SKREEM then waits for an RF signal response from the transponder. If the response received identifies the key as valid, the SKREEM sends a valid key message to the PCM over the CAN data bus. If the response received identifies the key as invalid or if no response is received from the key transponder, the SKREEM sends an invalid key message to the PCM. The PCM will enable or disable engine operation based upon the status of the SKREEM messages. It is important to note that the default condition in the PCM is an invalid key; therefore, if no message is received from the SKREEM by the PCM, the engine will be disabled and the vehicle immobilized after two seconds of running.
The SKREEM also sends security indicator status messages to the EMIC over the CAN data bus to tell the EMIC how to operate the security indicator. The security indicator status message from the SKREEM tells the EMIC to turn the indicator on for about three seconds each time the ignition switch is turned to the ON position as a bulb test. After completion of the bulb test, the SKREEM sends security indicator status messages to the EMIC to turn the indicator off, turn the indicator on, or to flash the indicator on and off. If the security indicator flashes or stays on solid after the bulb test, it signifies a SKIS fault. If the SKREEM detects a system malfunction or if the SKIS has become inoperative, the security indicator will stay on solid. If the SKREEM detects an invalid key or if a key transponder-related fault exists, the security indicator will flash. If the vehicle is equipped with the Customer Learn transponder programming feature, the SKREEM will also send messages to the EMIC to flash the security indicator whenever the Customer Learn programming mode is being utilized.
Removal & Installation
- Disconnect and isolate the battery negative cable.
- Grasp the tilt steering column knob firmly and pull it straight rearward to remove it from the tilt adjuster lever on the left side of the column.
- From below the steering column, remove the two outboard screws that secure the upper column shroud (1) to the lower shroud (3).
- Using hand pressure, push gently inward on both sides of the upper shroud above the parting line of the lower shroud to release the snap features that secure the two shroud halves to each other.
- Remove the upper shroud from the lower shroud and the steering column.
- Remove the one center screw that secures the lower shroud to the steering column (4).
- Remove the lower shroud from the steering column.
- Remove the screw (2) that secures the SKREEM (1) to the steering column housing.
- Disengage the antenna ring (3) from around the ignition lock cylinder housing (4) and remove the SKREEM.
- Position the Sentry Key Remote Entry Module (SKREEM) (1) onto the steering column with the antenna ring (3) oriented around the ignition lock cylinder housing (4).
- Install and tighten the screw (2) that secures the SKREEM to the steering column housing. Tighten the screw to 2 Nm (20 inch lbs.).
- Reconnect the wire harness connector (2) to the SKREEM (1).
- Position the lower shroud (3) onto the steering column (4).
- From below the steering column, install and tighten the one center screw that secures the lower shroud to the steering column. Tighten the screw to 2 Nm (20 inch lbs.).
- Position the upper shroud (1) onto the steering column over the lower shroud. On vehicles equipped with an automatic transmission, be certain to engage the gearshift lever gap hider into the opening in the right side of both shroud halves.
- Align the snap features on the upper shroud with the receptacles in the lower shroud and apply hand pressure to snap them together.
- Install and tighten the two outboard screws that secure the upper shroud to the lower shroud. Tighten the screws to 2 Nm (20 inch lbs.).
- Align the tilt steering column knob with the tilt adjuster lever on the left side of the steering column and use hand pressure to snap it back into place.
Reconnect the battery negative cable.
NOTEOn vehicles equipped with the optional Sentry Key Immobilizer System (SKIS) if the SKREEM is replaced with a new unit, a diagnostic scan tool MUST be used to initialize the new SKREEM and to program at least two Sentry Key transponders before the vehicle can be operated.