GENERAL INFORMATION
The wireless control module (WCM) is a system that integrates the keyless entry function, immobilizer function, and the TPMS function, and it has the following features
- The ignition key (transmitter) incorporates a lock/unlock switch and a panic alarm switch, and can be operated by remote control. The ignition key also incorporates an indicator light that enables the driver to check if the signal is transmitted correctly or if the battery in the key is discharged.
- The ignition key incorporates the immobilizer function that inhibits starting the engine by using an unauthorized key.
- The incorporated TPMS function monitors the air pressure of all the tires.
- Each vehicle is provided with two ignition keys (transmitter). Up to eight ignition keys can be registered.
- Settings of the keyless entry function can be adjusted using a customization function.
Scheme 1
| Parts name | Functional description |
|---|---|
| WCM | Controls the keyless entry functions, TPMS functions and starting of the engine by using the following communications. Communications with ETACS-ECU, ECK, ABS or ASC-ECU and combination meter via CAN Wireless communication with the ignition key (transmitter) Wireless communication with the TPMS transmitter |
| Ignition key (transmitter) | The ignition key (transmitter) receives signals sent from WCM, certifies the transponder ID code, calculates the encrypted code, and sends the reply data signal to WCM. The ignition key (transmitter) also sends signals to WCM when the lock/unlock switches on it are operated. Warning symbol and message is additionally displayed on the Multi information display. |
| Combination meter (Multi information display, TPMS warning light) | Communicates with WCM via CAN. Send ignition switch status. Receives the warning request or warning information from WCM, activates (1) the TPMS warning light. |
| ETACS-ECU | Communicates with WCM via CAN. Receives the door lock/unlock request from WCM, outputs the lock/unlock signal and flashes the turn signal light to inform the driver that the doors are locked/unlocked. |
| ABS or ASC-ECU | Communicates with WCM via CAN. Sends the vehicle speed data. |
| ECM | Communication with WCM via CAN. Send atmospheric pressure data. |
| TPMS transmitter | Measure tire pressure directly, then send radio frequency signal to WCM. |
| (1) Illuminates for tire pressure warning. Flashes for about 1 minute and then continuously illuminated for TPMS malfunction warning. | |
| (1) | Illuminates for tire pressure warning. Flashes for about 1 minute and then continuously illuminated for TPMS malfunction warning. |
MAIN COMPONENTS AND FUNCTIONS
Scheme 2
Note. In case of replacement of WCM, all keyless ID, key ID and tire pressure sensor ID should be re-registered using scan tool MB991958 (M.U.T.- III sub-assembly).
TECHNICAL DESCRIPTION (COMMENT)
If no data [ETACS transmits engine random number data to WCM via the CAN bus lines] is received from the engine control module via the CAN bus lines when the ignition switch is turned to ON position, it is judged as abnormal.
WCM determines that the abnormality is present when no VIN is recorded in it.
WCM determines that the abnormality is present, if the ignition key's encrypted code is not registered in WCM when the ignition switch is turned ON.
WCM determines that the abnormality is present, if the encrypted code for the ignition key does not match the one registered in WCM when the ignition switch is turned ON.
WCM determines that the abnormality is present, if the key certification result and the engine control module starting condition do not match after the engine start permission communication is completed.
WCM determines that the abnormality is present, if it cannot receive the encrypted code for the ignition key when the ignition switch is turned ON.
WCM determines that the abnormality is present, if it has detected discrepancy in the ignition switch level shown below ten consecutive times when WCM has received the CAN message (ignition switch position information) from ETACS-ECU with the ignition switch turned to the ON or START position.
B2101
- Status of ignition switch: OFF position
- Ignition switch position information from the ETACS-ECU: ON
B2102
- Status of ignition switch: ON position
- Ignition switch position information from the ETACS-ECU: OFF
WCM determines that the abnormality is present when the vehicle information registered in it does not match the vehicle information data.
WCM determines that the abnormality is present when VIN registered in it and the one that has been transmitted on the CAN bus do not match.
When the ignition switch is turned ON, WCM transmits signal to the antenna. When the antenna is found faulty, WCM determines that the abnormality is present.
WCM determines that the abnormality is present when the number of the transmitters registered in it is 0.
WCM determines that the abnormality is present, if the data abnormality is found when the ignition switch is turned ON and then EEPROM is written.
TECHNICAL DESCRIPTION(COMMENT)
If WCM cannot perform the data transmission in normal conditions due to a malfunction of the CAN-B bus circuit, WCM determines that there is a problem.
CIRCUIT OPERATION
WCM receives the vehicle information stored in the ETACS-ECU via CAN bus lines.
WCM communicates with scan tool via CAN. Therefore, communication error of WCM is suspected.
If only some ignition keys cannot be registered, the ignition key itself may be faulty. If no ignition key can be registered, the key assembly may have already been registered for another vehicle, or the WCM may be faulty.
If the fuel injection does not work, WCM and the MFI system may have a problem. This symptom is not considered abnormal when the engine is started by an ignition key that has not been registered.
OPERATION
The lock/unlock signals from the transmitter are received by WCM, and then sent to ETACS-ECU from WCM. When ETACS-ECU receives signals from the key reminder switch and all the door switches, ETACS-ECU actuates the keyless entry system.