Description And Operation: Operation
When the occupants of the front seats request the activation of the heated seats (two heating levels) or the steering wheel through the central control panel, the command is sent via Local Interface Network (LIN) data bus to the Body Control Module (BCM). The BCM translates the command received and sends it via Controller Area Network - BH (CAN-BH) to the Comfort Seat and Wheel Module (CSWM). The CSWM will supply the heater pads placed on the front seat backrests and cushions and will receive the signal directly from the two temperature sensors (one per seat) in the cushions, to learn the temperature of the seats and implement the correct strategies for supplying the heater pads. The heater pads in the steering wheel cover are supplied directly by the CSWM, while the temperature signal is received by the SWS (steering wheel switch unit) and sent via LIN to the BCM which will put it on the CAN network.
The CSWM monitors the operation of the system and will generate the appropriate DTCs in the event of failure.
When operating the heated seat switch, one of three switch positions can be selected: OFF, LOW, or HIGH. The CSWM can provide three levels of power to the heating elements for the HIGH setting. These power levels are changed by modulating the pulse width of the positive side of the circuit. The strategy used by the CSWM is to operate the heating element at the highest pulse-width until the target time or temperature for the pulse width is met. The CSWM then reduces the pulse width and repeats this process until the system times out. When the LOW setting is selected, the pulse width remains at 25% until the target temperature or time is reached (205 minutes for leather and 115 minutes for fabric). The following table provides an overview of the adjustment strategy used to control the amount of current provided to the seat heating elements:
| Parameter name | Definition | Unit | Leather | Fabric |
|---|---|---|---|---|
| Temp_OFF | Maximum temperature for heating program | °C/°F | 67/153 | 55 |
| DH_S3 | PWM for heating - high level 3 | s | 100% | 100% |
| Temp SH3 | Maximum temperature for seat heating level 3 | °C/°F | 50/122 | 34 |
| T1S | First timing program for seat heating | min. | 25 | 20 |
| DH_S2 | PWM for heating level 2 | s | 40% | 70% |
| Temp SH2 | Maximum temperature for seat heating level 2 | °C/°F | 55/131 | 38 |
| T2S | Second timing program for seat heating | min. | 85 | 35 |
| DH_S1 | PWM for heating level 1 | s | 40% | 34% |
| Temp SH1 | Maximum temperature for seat heating level 1 | °C/°F | 60/140 | 43 |
| T3S | Third timing program for seat heating | min. | 145 | 95 |
| DL_S1 | PWM for heating level Low | s | 25% | 25% |
| Temp SL1 | Maximum temperature for heating program Low | °C/°F | 65/149 | 48 |
| T4S | Fourth timing program for seat heating | min. | 205 | 115 |
- CSWM
- Cushion heater
- Backrest heater
- BCM
- SWS (steering wheel switch unit)
- Steering wheel heater
- CSS (central control panel)
- Cushion heater
- Backrest heater
- Clockspring
Power supply of the CSWM reaches from relay switch located in the Rear Power Distribution Center (PDC), through a circuit protected by a fuse.
Relay switch receives an ignition-operated power supply (INT) from the circuit protected by a fuse.
The control unit then connects via CAN data bus to the other network modules.
The BCM receives a direct power supply from the battery through the circuit protected by a maxi fuse located in the Battery Distribution Unit.
The BCM receives an ignition-operated power supply (INT). This signal is used, among other things, to "wake up the network".
The coil activation signal reaches the BCM via the LIN bus.
Controls for the steering wheel coil are sent through the clockspring, whose control thermostat is located in the steering wheel controls.