Description And Operation
DESCRIPTION
The Comfort Seat and Wheel Module (CSWM) (1) is located under the passenger front seat. It has a minimum of two electrical connectors and a maximum of four electrical connections, and a push pin style retainer that secures it to the seat pan. The module can be accessed from under the passenger seat with the seat in the full back and up position.
The CSWM is a Controller Area Network - Interior High Speed (CAN-IHS) bus microcontroller providing outputs to the heated seat pads, heated steering wheel, and ventilating up to two seats. The CSWM receives commands over the CAN-IHS bus from the Body Control Module (BCM). The seat thermistor is hard wired to the CSWM.
Heated Seats - The CSWM uses a Pulse Width Modulation (PWM) to provide power to the seat cushion and back heating elements. The temperature sensor thermistor is located in the seat cushion. The thermistor sensor feedbacks from each seat heating element to the CSWM to regulate the heater outputs to prevent any seat temperature to rise above set points. Seat heating has two selectable heat settings which are HI and LO. Depending on thermistor reading, the CSWM will start the heater output by adjusting the PWM heat level according to the calibration table.
Heated Steering Wheel - The CSWM provides power to the steering wheel heating element. The heated steering wheel is standard when the vehicle is equipped with front heated seats. During normal operation, the CSWM will switch on the power for the heated wheel only if the engine is running. The heated steering wheel temperature sensor is hard wired to the Left LIN Steering Wheel Control Switch which sends that information over a Local Interface Network (LIN) bus through the Steering Column Control Module (SCCM) to the BCM. The thermistor sensor feedbacks from the steering wheel heating element via the CAN-IHS bus to the CSWM regulating the heater output to prevent the wheel temperature to rise above the maximum threshold temperature set point.
OPERATION
The CSWM operates on fused battery current received from the ignition switch. The module is grounded to the body at all times through the electrical connector. Inputs to the module include CAN-IHS bus data bus messages and standard hard wired 12 volt power and ground. In response to inputs, the CSWM will control the battery current to the appropriate heated seat elements.
When a heated seat switch IHS data bus signal is received by the CWSM, the module energizes the selected heated seat element. The Low heat set point is about 38°C (100.4°F), and the High heat set point is about 42°C (107.6°F).
The CSWM will automatically transition the output from high to low after a maximum period of 60 minutes has elapsed. The CSWM will automatically transition the output from low to off after a maximum period of 45 minutes has elapsed.
In addition to operating the heated seat elements, the heated seat module sends LED illumination messages to the IPC. The IPC then sends the LED illumination message to the Integrated Center Stack (ICS) so that the appropriate LEDs are illuminated for any given heating level. Pressing the switch once will select high-level heating. Pressing the switch a second time will select low-level heating. Pressing the switch a third time will shut the heating elements off.
If the CSWM detects a heated seat element OPEN or SHORT circuit, it will record and store the appropriate Diagnostic Trouble Code (DTC).
Driver Seat Heat Systems
- The element consists of a cushion element connected in parallel with a back element.
- The seat cushion has a thermistor to provide feedback to the CSWM.
- The heated seat cushion and seat back have a thermostat to automatically open the feed to turn the heated seat system off if the temperature reaches or exceeds the operating parameters programmed to the CSWM.
The CSWM is diagnosed using a scan tool. If the module detects a heated seat element OPEN or SHORT circuit, the system will turn off and it will record and store the appropriate Diagnostic Trouble Code (DTC). Refer to DIAGNOSTIC CODE INDEX .