Everybody,

Please read the description of all the stuff the SKREEM module is responsible for. One is the termination resistor for the CAN C buss for all of the modules to communicate. No termination no data between modules. It is the storage for DRBIII diagnostic codes. Etc., etc.

OPERATION
VEHICLE LOCKING / UNLOCKING

To unlock, the SKREEM module sends a signal to the Body Control Module. The Body Control Module then sends a signal to the Central Locking Pump/Security System Module (CLP/SSM) via the Controller Area Network (CAN) Bus. The CLP/SSM pump motor starts running and supplies air pressure. The door lock actuators are pressurized. When a pressure threshold is reached in the system, the pump is switched off by an internal pressure switch. The pressure in the system is then released by the CLP/SSM and the unlocking operation is completed. The locking procedure is accomplished in a fashion opposite to the unlocking operation. However, the next time the remote control button is pressed, the CLP/SSM is also actuated by connecting it to ground by the second control lead on the SKREEM module. The direction of rotation for the CLP/SSM pump motor is reversed, thereby providing the vacuum required to lock. In order to avoid unlocking the vehicle unintentionally, the vehicle is relocked by the CLP/ SSM via the SKREEM module. After unlocking with the remote control, the locks will be relocked if either door is not opened within 40 seconds, the key is not inserted into the ignition switch, or the interior power door lock switch is not actuated. The CLP/SSM reads the signals (door contacts, liftgate/decklid, interior power door lock switch) and actuates the power door lock actuators. The vehicle security alarm is also activated by the relocking function.

AUTOMATIC LOCKING / UNLOCKING

Upon reaching a speed of 15 km/h (9 MPH), the vehicle doors are locked automatically. The fuel tank flap remains unlocked. If, after automatic locking, the vehicle is unlocked with the interior power door lock switch, this state is maintained until a door is opened or until the ignition is switched off. Automatic locking is accomplished again only upon reaching the specified speed. The logic circuitry for this function is integrated into the CLP/SSM. The auto- matic locking function can be activated or deactivated with the DRB III��. An alternative is to use the interior power door lock switch with the ignition switched on by pressing and holding the door lock switch for more than 5 seconds in either the lock (auto locking switched on) or unlock (auto locking switched off) position. The alternative of enabling/disabling the auto locking system by using the interior power door lock switch can also be inhibited with the DRB III��.

EMERGENCY UNLOCKING

In the event of a vehicle collision, the doors are unlocked automatically by a crash sensor integrated into the CLP/ SSM. The doors are unlocked after a delay time of 8 to 11 seconds. The emergency unlocking function interrupts all functions performed by the CLP/SSM, which are reactivated only after interrupting the ignition. The emergency unlocking function is only active when the vehicle is unlocked from the outside.

VEHICLE RELOCKING

In order to avoid unlocking the vehicle unintentionally, the vehicle is relocked by the CLP/SSM via the SKREEM module. Relocking is accomplished after unlocking with the remote control when: a door is not opened within 40 seconds, the key is not inserted into the ignition lock, or the interior power door lock switch is not actuated. The CLP/SSM reads the signals (door contacts, interior power door lock switch) and actuates the power door lock actua- tors. The vehicle security alarm is also activated by the relocking function.

OPERATION

The Sentry Key Remote Entry Module (SKREEM) has the following functions: receiving and evaluating the Radio Frequency (RF) keyless entry remote signal, actuation of door locks in conjunction with the Central Locking Pump/ Security System Module, and enabling the vehicle theft security alarm with confirmation via the turn signals. When the RKE transmitter is operated, an RF signal is transmitted. If the SKREEM recognizes the RF signal as valid, it actuates the Central Locking Pump/Security System Module through the Body Control Module. The vehicle is then locked or unlocked through the power locks system. Connected to the SKREEM is a Sentry Key Antenna Ring which surrounds the ignition lock cylinder. When the ignition is switched on, the Sentry Key Antenna Ring is sup- plied with power. A data block is transmitted inductively via the Sentry Key Antenna Ring to the SKREEM and then on to the Powertrain Control Module. If the antenna ring data block content is invalid or if vehicle battery power is too low to build up enough power for the antenna ring, the Powertrain Control Module will not receive the proper signal. This is displayed with the message “Start Error” in the Instrument Cluster.

The SKREEM contains an RF transceiver and a microprocessor. The SKREEM transmits RF signals to and receives RF signals from the ignition key transponder through a tuned Sentry Key Antenna Ring that is wired to the SKREEM. If the Sentry Key Antenna Ring is not mounted properly around the ignition lock cylinder housing, com- munication problems between the SKREEM and the ignition key may arise. These communication problems will result in ignition key transponder-related faults. The SKREEM also communicates over the Controller Area Network (CAN) data bus with the Powertrain Control Module (PCM), the Instrument Cluster, the Body Control Module (BCM), and/or the DRB III�� scan tool.

The SKREEM retains in memory the ID numbers of any ignition key transponder that is programmed into it. For added system security each SKREEM is programmed with a unique secret key code. This code is stored in mem- ory, sent over the CAN data bus to the PCM, and is encoded to the transponder of every ignition key that is pro- grammed into the SKREEM.

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 DRB III�� scan tool and the ignition key system replacement programming procedure. Proper completion of the ignition key system initialization will allow the existing ignition 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 ignition keys. The DRB III�� scan tool will alert the technician during the key reprogramming procedure if new ignition keys are required.

The sentry key system performs a self-test each time the ignition switch is turned to the ON/RUN position and will store fault information in the form of Diagnostic Trouble Codes (DTCs) in SKREEM memory if a system malfunction is detected. The SKREEM can be diagnosed and any stored DTCs can be retrieved using a DRB III�� scan tool. Refer to the appropriate diagnostic information.