Compass 2WD L4-2.4L (2008)
Seat Heater: Description and Operation
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 12v output to the front seat heating elements through integral solid-state relays.
When either of the heated seat switches are depressed a switch status message is sent to the Cab Compartment Node (CCN) or instrument cluster via the
Local Interface Network (LIN) data bus. The CCN then sends a message via the LIN data bus to the heated seat module, signaling the module to
energize the heating element for the selected seat. 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. The heated seat module sends the LED illumination message to the CCN via the
LIN data bus. The CCN then sends the LED illumination message to the accessory switch bank so that the appropriate LEDs are illuminated for any
given heating level. 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.
The heated seat module energizes an integral solid-state relay, which supplies battery current to the heating elements. When high-temperature heating is
selected, the heaters provide a boosted heat level during the first four minutes of operation after heating is activated once per ignition cycle. The heat
output then drops to the normal high-temperature level. If high-level heating is selected, the control system will automatically switch to the low level
after thirty minutes (twenty six minutes on first activation of an ignition cycle) of continuous operation. At that time, the number of illuminated LEDs
changes from two to one, indicating the change. Operation on the low setting also turns off automatically after thirty minutes.
The module will automatically turn off the heating elements if it detects an OPEN or LOW short in the heating element circuit. In the event an OPEN or
LOW short in the heating element circuit is detected when the heated seats are first initialized, the two LEDs will light for two seconds and go out as an
indicator of a system problem.
