Principles Of Operation

Seats

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 outputs voltage and ground to the power seat motor assembly to move the driver seat. The DSM monitors the seat position sensors to return the seat to a stored position.

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.

NOTE: 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.

NOTE: 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 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 with rear heated seats are equipped with 2 rear heated seat modules, one for each LH and RH seating position. Rear heated seat modules are located behind the rear seat backrest behind the LH and RH seat positions.

Front and rear heated seat system operation is similar. The system only operates with the engine running. When the heated seat switch is pressed, 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 backrest heater mat are wired in series. When the system is on, the heated seat module supplies ground to the heated seat switch to illuminate the indicator. Rear heated seats turn off after 10 minutes. Front heated seats do not time-out. The heated seat modules monitor temperature sensors in the cushion heater mats and regulate the outputs to the heater mats to maintain seat temperature until switched off or a time-out occurs (rear only).