Seat Temperature Switch: Description and Operation

SWITCH-HEATED SEAT

HEATED SEAT SWITCH

DESCRIPTION




The heated seat switches are both mounted in the instrument panel. The two switches are snapped into mounting holes in the instrument panel center bezel (1). The two heated seat switches (2) and (3) are identical in appearance and construction, except for the location of a keyway in the connector receptacle on the back of each switch. The instrument panel wire harness connectors for the heated seat switches are keyed to match the connector receptacles so that the two heated seat switches can only be connected to the proper heated seat.




Each momentary, bidirectional rocker-type heated seat switch provides a resistor-multiplexed signal to the Cab Compartment Node (CCN). Each switch has a center neutral position and momentary Low and High positions so that the driver and the front seat passenger can select a preferred seat heating level. Each heated seat switch has two Light-Emitting Diode (LED) indicator lamps, which indicate the selected level (Low or High) of the seat heater. Each switch also has one indicator lamp for back lighting of the switch when the ignition switch is in the Run position.

The five LED indicator lamps in each heated seat switch cannot be repaired. If the LED lamps are faulty or damaged, or the switch is faulty or damaged the individual heated seat switch assembly must be replaced.

OPERATION
The heated seat switches receive battery current through a fused ignition switch output (run) circuit when the ignition switch is in the On position. Depressing the heated seat switch rocker to its momentary High or Low position provides a hard-wired resistor multiplexed signal to the Cabin Compartment Node (CCN). The CCN is responsible for supplying the CAN bus message to the heated seat module, signaling the module to power the heated seat element of the selected seat and maintain the temperature setting.

If the heated seat switch is depressed to a different position (Low or High) than the currently selected state, the CCN will go through the process again to change the temperature setting. If a heated seat switch is depressed a second time to the same position as the currently selected state, the CCN and heated seat module interprets the second input as a request to turn the seat heater OFF. The CCN will then signal the heated seat module to turn the heated seat elements for that seat off.

The backlighting LED's in each of the heated seat switches receive battery current through a fused ignition switch output (run) circuit when the ignition switch is in the On position. The ground side of the indicator lamp is divided by a separate lamp driver circuit in the CCN.