Grand Cherokee 2WD V6-3.7L (2008)
Seat Heater Switch: Description and Operation
Operation
Front Seats
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. When
either of the front heated seat switches are depressed a resistance signal is sent to the ElectroMechanical Instrument Cluster (EMIC) (also known as the
Cab Compartment Node/CCN). The instrument cluster receives this message via the Local Interconnect Network (LIN) data bus. The instrument cluster
then sends a message via the Controller Area Network (CAN) data bus to the heated seat module, signaling the module to energize the heating element
for the selected seat.
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.
2nd Row
OPERATION
The heated seat switches for the 2nd row seats are located in the rear center floor console. Amber Light Emitting Diodes (LEDs) in the top portion of
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 switch a second time will select low-level heating. Pressing the switch a third time will shut the heating elements off.
When either of the 2nd row heated seat switches are depressed a hardwired resistance signal is sent to the ElectroMechanical Instrument Cluster (EMIC)
(also known as the Cab Compartment Node/CCN). The instrument cluster then sends a message via the Controller Area Network (CAN) data bus
network to the heated seat module, signaling the module to energize the heating element for the selected seat. Light Emitting Diodes (LED) in each
switch indicate the level of heat in use. The switch LEDs are controlled by the instrument cluster.
