Heated Seat Module - Operation

OPERATION

The Heated Seat Module (HSM), also known as the Comfort Seat Wheel Module (CSWM), controls the heated seat system and the heated steering wheel system, when equipped. The HSM responds to heated seat and steering wheel switch messages and ignition status inputs and controls the 12 volt Direct Current (DC) output to the heating elements through integral solid-state relays.

When either of the front heated seat switches are pressed, a resistive signal is sent to the Cabin Compartment Node (CCN) over hard-wired circuits. The CCN then sends a request signal over the Controller Area Network (CAN) data bus to the HSM, to supply power to the heating elements for the selected seat. When high-level heating is initially selected, the HSM provides a boosted heat level during the first four minutes of operation, then the heat output level drops to normal high setting. When high setting is first selected, the HSM will automatically switch to low-level temperature after approximately thirty minutes of continuous operation. At that time, the number of illuminated indicator lamps in the heated seat switch change from two to one, indicating the temperature level change. Operation on low-level turns off automatically after approximately thirty minutes.

When equipped with a heated steering wheel, pressing the heated steering wheel switch provides a resistive signal over a hard-wired circuits to the CCN. The CCN sends a request signal over the CAN data bus to the HSM, signaling the HSM to power the heating element for the steering wheel.

The heated seat and steering wheel systems operate on battery current received through a fused ignition Run circuit, so that the system will only operate when the engine is running. With a heated seat or steering wheel on, if the ignition is set to any position other than Run, the heated system will turn off, and remain off, until the engine is restarted and a heated seat or steering wheel switch is pressed again.

The HSM is diagnosed using a scan tool and will automatically turn off the heating elements if it detects an open or low short in a heating element circuit Testing and Inspection.