Principles of Operation (How Does It Work?)
Principles of Operation (How Does It Work?) / Power Seats With Memory
Seat Positioning - Seat Control Switch
The six-way power seat is controlled by the driver seat module (DSM) only when the vehicle is equipped with the memory driver seat option. The DSM will power the forward/rearward or up/down motion of the motor until the corresponding seat control switch is released or until end travel is reached.
Seat Positioning - Memory Feature
A power driver seat feature allows the driver to program a personalized seat position that can be recalled using the memory switches or remote keyless entry (RKE) key fob. There are two memory settings possible.
A power driver seat position can be stored at any time. To store the power driver seat position to memory, the driver must move the seat to the preferred position using the driver seat control switch assembly. The driver must then depress the memory set switch. In response to this, the DSM will activate the memory set switch LED and initialize a 5.0 ± 1.0 second timer. The driver then has 5.0 ± 1.0 second to select a memory position.
Memory 1 is selected by depressing and holding the memory switch 1 for 100.0 milliseconds.
Memory 2 is selected by depressing and holding the memory switch 2 for 100.0 milliseconds.
If no memory switch input is received within the 5.0 ± 1.0 second time limit, the operation is aborted and the memory set switch LED is turned off.
If one of the following inputs is received during the 5.0 second programming window, the operation is aborted and the memory set switch LED is turned off:
- Power driver seat control switch.
- Memory set switch.
Upon detection of a completed memory set process, the DSM will save power driver seat positions and adjustable pedal positions in the appropriate memory (1, or 2). The DSM derives seat position information (front height, rear height, forward/rearward) from the driver seat position sensors.
NOTE: A memory recall can only be initiated if the vehicle is in PARK or NEUTRAL gear and the ignition switch is not in START. An ongoing memory recall will not be affected by moving the ignition switch to START, nor by moving the gearshift lever out of PARK or NEUTRAL.
Once the driver has stored a preferred driver seat position, the driver can recall the setting by depressing the corresponding memory switch or by using a programmed RKE key fob. The driver can recall a preferred driver seat position by using one or both of the memory recall switches.
Pressing and holding memory switch 1 for 100.0 milliseconds will initiate a recall of the power driver seat position stored in memory number 1.
Pressing and holding memory switch 2 for 100.0 milliseconds will initiate a recall of the power driver seat position stored in memory number 2.
A RKE key fob (security module interface) can be used to recall previously set memory positions. The key fob assigned with personality Number 1 is capable of recalling only memory position 1. The personality Number 2 key fob can recall only memory position 2.
Memory recall occurs when the UNLOCK switch is pressed on the key fob. The second depression of the UNLOCK switch, which unlocks passenger doors, does not initiate a memory recall.
An ongoing memory recall does not prohibit the initiation of another memory recall; the most recently requested memory recall will be executed. If the driver seat control switch is activated during a memory recall, the memory recall seat movement will stop and the switch commands will be executed. Activation of the memory set switch will also cancel a memory recall in progress.
Memory positions that have been programmed will not initiate any motion for the power driver seat.
Power Seat Calibration Test
The driver seat module (DSM) is calibrated using the scan tool. The calibration procedure automatically powers the seat through its full range of motion and records the full stop position by monitoring the motor position sensors. Once the full stop position or range of the seat has been recorded, the DSM will operate only within the calibrated range. Any inputs attempting to drive the seat beyond the calibrated range will be ignored. This calibration is used for all seat control functions, including manual switch control and memory recall positioning. During the seat calibration, the DSM may identify a function that is inoperative, such as a position sensor not changing. If the DSM identifies a concern that has a related diagnostic trouble code (DTC), the DSM will set the related DTC at the end of the validation procedure.
The calibration procedure powers the seat track adjustments to the end of their travel, which is determined by the DSM seeing a change of state in the motor position sensors. If there is a concern with the seat track or motor position sensor that limits travel, the DSM will interpret the stopping point as the end of travel and store the position. The DSM is not able to determine if the seat has moved to its full travel position, it is only capable of monitoring and storing the amount of travel seen by the position sensor changing states.
Principles of Operation (How Does It Work?) / Power Seats Without Memory
The six-way power seat feature moves the seat in six possible directions: the base of the seat can be moved forward or backward and the front and back of the base cushion can be moved up or down independent of the position of the ignition.
Principles of Operation (How Does It Work?) / Heated Seats
The driver and passenger heated seats share a common battery and ignition feed. A separate shared ignition source supplies the heated seat control switches. When the heated seat control switch is pressed with the ignition switch in RUN or START, a momentary voltage signal is sent to the heated seat module. The heated seat module then supplies power to the heating element circuit. The cushion element and seat backrest element are wired in series and powered by the same output. The heated seat module also will ground the separate indicator circuit at the dual automatic temperature control (DATC) module display panel to indicate an ON state. The heated seat module will remain on until the heated seat control 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 until the module is switched off. This temperature is maintained by the heated seat module monitoring the temperature sensor located in the seat cushion element and adjusting the current flow to the heating elements.