Heated Seats - Operation

OPERATION

The heated seat system operates on battery current received through a fuse in the Totally Integrated Power Module (TIPM). Fused ignition switch output (run) circuits are used, so that the heated seat system will only operate when the ignition switch is in the On position. The heated seat system will turn off automatically whenever the ignition switch is turned to any position except On.

A Heated Seat Module is used to control the heated seat system. The module responds to heated seat switch messages and ignition switch status inputs by controlling the electrical output to the front seat heating elements through integral solid-state relays.

When either of the heated seat switches are pressed, a resistance signal is sent to the Cab Compartment Node (CCN) over the Local Interface Network (LIN) data base. The CCN then sends a request message over the LIN bus to the heated seat module, signaling the module to energize the heating elements for the selected seat. Amber Light Emitting Diodes (LEDs) in each heated seat switch indicate the level of heat in use: Two LEDs illuminate for high, one for low, and none for off. Pressing a heated seat switch once will select high-level heating and pressing the same switch a second time will select low-level heating. Pressing the switch a third time will shut the heating elements off.

The heated seat module energizes an integral solid-state relay, which supplies battery current to the heating elements. When high-level heating is first selected, the module provides a boosted heat level during the first four minutes of operation. After the initial four minutes of operation, the heat output then drops to the normal high-level temperature. If high-level heating is initially selected, the heated seat control system will automatically switch to the low-level temperature after thirty minutes of continuous operation. At that time, the number of illuminated LEDs change from two to one, indicating the temperature change. Operation in the low-level setting automatically turns off after thirty minutes.

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