Heated Seat Module

Heated Seat Module






Description

The Heated Seat Module (HSM) (2), also know as the comfort seat wheel module, is located under the driver side front seat. It has a single electrical connector (1) and a push pin style retainer that secures it to the seat pan. The module can be accessed for service from under the driver seat.

The HSM is a microprocessor designed to use the Local Interface Network (LIN) data bus messages from the instrument cluster, also known as the Cabin Compartment Node (CCN). The CCN receives inputs from the heated seat switches and rear door modules over the Controller Area Network (CAN) bus, and in turn, signals the HSM to operate the heating elements for the selected seats.

Operation

The Heated Seat Module (HSM), also know as the comfort seat wheel module, is used to control the heated seat system. The HSM responds to heated seat switch and ignition switch status inputs and controls the 12 volt Direct Current (DC) output to the seat heating elements through integral solid-state relays.

The front seat heated switches send a request signal to the Cabin Compartment Node (CCN) over the Controller Area Network (CAN) bus. The rear heated seat switches send a hardwired resistance signal to the rear door modules, which send the request signal to the CCN over the CAN bus. The CCN then signals the HSM to operate the heated seat.

The heating elements for the selected seat are energized when any of the heated seat switches are pressed. Light Emitting Diodes (LEDS) on each switch indicate the level of heat in use: Two LEDs are illuminated for high, one for low and none for off. Pressing the switch once will select high-level heating. Pressing the same switch a second time will select low-level heating. Pressing the switch a third time will shut the heating elements off.

When high-level heating is initially selected, the heated seat control logic provides a boosted high heat level during the first four minutes of operation, and then lowers the heat level to the normal high temperature level. After thirty minutes of continuous operation on high heat, the heated seat control logic lowers the seat temperature to the low level. At that time, the number of illuminated LEDs change from two to one, indicating the temperature setting change. Operation on the low-level heat setting also turns off after thirty minutes.

The heated seat system will automatically turn off if an open or short in the heating element circuit is detected.