HEATED SEAT ELEMENT
DESCRIPTION
Vehicles equipped with the optional heated seat sys-
tem have two sets of electrically operated heating ele-
ment grids located in each front seat, one set for the
seat cushion and the other set for the seat back. Each
of the heated seat element grids consists of a single
length of resistor wire that is routed in a zigzag pattern
and captured between a covering and the adhesive
foam rubber backing. Short pigtail wires with connec-
tors are soldered to each end of each resistor wire
element grid, which connect all of the element grids to
the heated seat module through the seat wire har-
ness.
One temperature sensor is used for each front seat,
and it is located in the center insert area of the seat
cushion element. The heated seat sensors and their
pigtail wires are also captured between a covering and
the adhesive foam rubber backing. The heated seat
sensors are Negative Thermal Coefficient (NTC) ther-
mistors. The sensors for both front seats receive a
voltage feed from a single output of the heated seat
module, but the module receives individual sensor
inputs from the driver side and passenger side sen-
sors.
The heated seat elements and sensors should not be repaired. If damaged or faulty, the heated seat element
assembly must be replaced.
OPERATION
One end of the heated seat element resistor wire is connected to ground at all times through a splice in the heated
seat module ground circuit. Battery current is directed to the other end of the heated seat element resistor wire by
the energized N-channel Field Effect Transistor (N-FET) located within the heated seat module. The heated seat
module will energize the N-FET only when the heated seat switch is in the Low or High position and the heated seat
sensor indicates that the seat cushion surface temperature is below the selected (Low or High) temperature set
point. As electrical current passes through the heating element grid, the resistance of the wire used in the element
disperses some of that electrical current in the form of heat. The heat produced by the heated seat element grid
then radiates through the seat trim cover, warming its occupant.
The resistance of the heated seat sensor increases and decreases as the surface temperature of the seat cushion
cover changes. The heated seat module supplies each sensor with a 5v voltage feed, then uses the sensor resis-
tance to determine when the heated seat element grids need to be cycled on or off in order to maintain the selected
temperature set point.
DIAGNOSIS AND TESTING
HEATED SEAT ELEMENT
The heated seat module will self-diagnose shorted or open heated seat element circuits and sensor circuits. (Refer
to 8 - ELECTRICAL/HEATED SEATS - DIAGNOSIS AND TESTING) for additional diagnosis and testing procedures.
To manually check the heated seat element, proceed as follows. The wire harness connectors for the seat cushion
and seat back heating elements and sensor are located on the right side of the seat, near the edge of the seat
cushion frame. The proper connector can be identified by the foam wrapping.
8G - 20
HEATED SEATS - SERVICE INFORMATION
DR/DH