Principles of Operation

PRINCIPLES OF OPERATION

Front Power Seats
The driver and front passenger power seat motors are hardwired to the seat control switches on each respective front door trim panel. The circuits are normally at ground through the seat control switch. Each individual seat track or recliner motor circuit (if equipped) is switched to voltage when the specific adjustment position is selected.

Memory Seat
The driver power seat is controlled by the driver seat module (DSM). The driver seat control switch circuits are connected to inputs on the driver door module (DDM) and apply fused voltage to the DDM inputs. The DDM communicates the seat control switch position by transmitting signal data to the DSM using the standard corporate protocol (SCP) communication bus. The received signal data causes the DSM to apply voltage directly to the appropriate seat motor. Toggling the seat control switch in the opposite direction changes the input to the DDM and the signal transmitted to the DSM causing it to apply voltage to the opposite seat motor circuit. Ground is the normal state of the motor circuits through the DSM. The DSM internally switches the appropriate circuit from ground to voltage to adjust the motors.

As the seat is adjusted, the DSM constantly monitors the motor position sensors to record the current seat position. The DSM will remove voltage from the motor upon termination of the seat control switch input or if the DSM does not see movement from the motor by monitoring the seat position sensor.

Memory seat positioning can be recalled with the memory switches on the driver door panel or a programmed remote keyless entry (RKE) transmitter. In either case, the DSM receives a memory recall 1 or 2 command from the DDM over the SCP communication network. The memory recall switches are a hardwired input to the DDM. The DDM also receives the RKE transmitter signals. Once a valid memory recall command is received from the DDM, the DSM moves the driver seat to the position stored in memory by powering the appropriate motors and monitoring the motor position sensors until the position is reached.

For information on programming memory positions or recalling a stored memory position, refer to Memory Position Programming. Programming and Relearning

Heated Seats

NOTE:
- If a passenger seat cushion heater mat is inoperative, a new occupant classification sensor (OCS) system service kit must be installed and a new cushion heater mat must be installed to the OCS system service kit foam pad.
- When installing an OCS system service kit equipped with heated seats, a new seat cushion heater mat must be installed. Do not reuse the OEM OCS cushion heater mat. The OCS system service kit does not come with a cushion heater mat.
- When installing a new driver seat heater mat (cushion or backrest) or passenger seat backrest heater mat, a new foam pad with the heater mat already attached is required. A new seat heater mat by itself is not available for service for the driver seat.

Vehicles equipped with front heated seats are equipped with a heated seat module which controls both front heated seats. The heated seat module is located behind the front passenger door trim panel.

Vehicles equipped with rear heated seats are equipped with 2 rear heated seat modules, one for the left rear heated seat and the other for the right rear heated seat. Each rear heated seat module is located underneath the respective rear seat backrest trim cover.

The functionality of both the front and rear heated seat systems is similar. When the heated seat switch is pressed with the ignition switch in RUN, a momentary voltage signal is sent to the heated seat module. The heated seat module then supplies voltage to the heater circuit. The cushion heater mat and seat backrest heater mat are wired in series and powered by the same output. The heated seat module also will ground the separate indicator circuit at the heated seat switch to indicate an ON state. The front heated seat module will remain on until the heated seat switch is pressed and a momentary voltage signal is received or the ignition switch is set to OFF. The rear heated seat modules will remain on until the heated seat switch is pressed and a momentary voltage signal is received, or until 10 minutes expire. If the ignition source is removed from the module, the heated seat module will enter an OFF state and will not return to ON until the switch is once again pressed with the ignition switch in RUN. The heated seat module is designed to heat the seat to 37.5°C (99.5°F) and maintain the temperature until time-out or switched off. This temperature is maintained by the heated seat module monitoring the temperature sensor located in the seat cushion heater mat, and adjusting the current flow to the heater mats.