Purpose of the VSM block
In addition to the function of controlling the operation of various electrical units, the BCM unit provides the function of reading the operating mode of the combined switch (lighting, windshield wipers and washers, direction indicators). In addition, it has an interface that allows you to receive signals from the A/C amplifier and send signals to the ECM via the CAN bus.
Combination switch operation mode reading function
The BCM reads the operating status of the combination switch (switch for headlights, wiper and washer, direction indicators) and controls various electrical components according to the information received.
The BCM unit reads information from 20 switches and 5 diagnostic results by combining five output contacts (OUTPUT 1 -5) and five input contacts (INPUT 1 -5).
Systems controlled by the VSM unit
- Electric door locks
- super castle
- Remote control door locks
- Power windows
- Interior lighting timer
- Sound alarm
- Turn signal and hazard warning lights
- Rear window cleaner
- Rear fog lamp
Systems managed by VSM and IPDM E/R units
- Anti-theft system (NATS)
- windshield wiper
- Windshield washer
- Rear window heater
- Fog lights
- headlight washer
Systems controlled by BCM units and smart key
- smart key
Input/output signals
System | Input signal | Output signal |
Remote control door locks | Remote control |
|
smart key | Smart key block |
|
Power door locks/ Superlock |
|
|
Power supply (IGN) glass lifts | Ignition power supply |
|
Power supply (BAT) power windows | Battery power supply |
|
headlights | combination switch | Block IPDM E/R (headlight relay) |
Tail light | combination switch | Block IPDM E/R (tail light relay) |
Rear fog lamp | combination switch | Rear combination lamp (rear fog lamp) |
Direction indicator lamp | combination switch |
|
Hazard lights | Hazard switch |
|
Interior lighting timer |
| Elephant lampshade |
Audible alarm for ignition key reminder |
| instrument cluster (buzzer) |
Lighting Reminder Sound Alarm |
| instrument cluster (buzzer) |
Windshield wiper with rain sensor |
| IPDM E/R block (windshield wiper relay) |
Windshield washer | combination switch | Washer motor |
Rear window cleaner | combination switch | Rear wiper motor |
Rear window washer | combination switch | Rear window washer motor |
Headlight washer | Headlight washer switch | Headlight washer relay (via IPDM E/R block) |
Rear window heater |
| IPDM E/R block (rear window defroster relay) |
Button signal «A/C» | A/C Amplifier | ECM block |
Signal from blower fan button | A/C Amplifier | ECM block |
CAN bus control
The CAN bus allows information to be transmitted at high speed over two communication lines (CAN L and CAN H), which combine various control units into a system. All control units transmit and receive data, but selectively read only the required data.
BCM state management
The BCM unit changes its state depending on the operating mode to save energy.
1. Status of communication via the CAN bus.
When the ignition key is turned to position «ON» the BCM exchanges information with other control units.
The BCM unit performs normal control.
When the ignition key is turned to position «OFF» it is possible to switch to «sleeping» mode.
Even when the ignition key is turned to «OFF», if communication with the IPDM E/R unit and instrument cluster is active, then the communication status via the CAN bus is active.
2. Transition state in «sleeping» mode.
In this state, communication via the CAN bus is disabled when the ignition key is turned to the «OFF».
The IPDM E/R unit and instrument cluster are requested to change to «sleeping» mode.
Two seconds after the termination of communication via the CAN bus between all control units, the exchange of information via the CAN bus switches to an inactive state.
3. Inactive state of communication via the CAN bus.
When the ignition key is turned to position «OFF» communication status via CAN bus is inactive.
When the ignition key is turned to position «OFF» active control, carried out only by the BCM unit.
Two seconds after the termination of communication via the CAN bus between all control units, the exchange of information via the CAN bus switches to an inactive state.
4. «Sleeping» mode.
The BCM is activated in low power mode.
CAN bus is not active.
When determining the CAN bus operating state, it switches to the CAN bus communication state.
When the switch is requested to be controlled by the BCM only, it switches to the inactive state of communication via the CAN bus.
It changes the reading function of the combination switch.