Heated Seat Module - Operation

OPERATION

The Heated Seat Module (HSM), also known as the comfort seat wheel module, controls the heated seat system. The HSM responds to heated seat switch messages and ignition status inputs by controlling the 12 volt Direct Current (DC) output to the seat 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.

The heated seat system operates 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 on, if the ignition is set to any position other than Run, the heated seat system will turn off, and remain off, until the engine is restarted and a heated seat 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.