Principles Of Operation - Heated Seats

Seats

Principles of Operation - Heated Seats

Heated Seats

The heated seat system only operates when the engine is running. When the heated seat switch(es) (located on the instrument panel) is activated, it supplies a ground signal to the Body Control Module (BCM). When the BCM (Body Control Module) receives the heated seat switch signal, it activates the appropriate (driver or passenger) heated seat relay, (located in the Central Junction Box (CJB). When the heated seat relay is activated, voltage is supplied to the cushion heater mat. The cushion heater mats are directly connected to ground to complete the electrical circuit to heat the seat.

Each cushion heater mat contains a non-serviceable internal thermostatic switch that closes when cold to complete the heater grid circuit and heat the seat. When hot, the thermostatic switch opens the heater grid circuit and allows the seat to cool. During normal operation, several minutes may be required before seat temperature is increased and several more minutes of cooling before the heater mats continue with heating. The heated seat indicator illuminates continuously while the thermostatic switch cycles between open and closed.

The seat should be occupied to correctly test for normal operation. Temperature measuring devices do not provide an accurate method for testing heated seat operation as surface temperatures are subject to human and environmental characteristics. Correct testing requires heater mat resistance measurements which have tight tolerances affecting heat cycle time length.

The heated seat system does not time-out. A heated seat remains on until it is turned off by the heated seat switch or the ignition is switched OFF.