Principles of Operation

PRINCIPLES OF OPERATION

Driver and Passenger Power Seats Without Memory
The driver power seat uses a 6-way power seat track and 3 electric motors directly controlled by a seat mounted 6-way seat control switch for horizontal (forward/rearward), front height and rear height adjustment. The power seat feature operates independent of the ignition switch position.

The driver and passenger power seat motors are hard-wired to the seat control switch. The circuits are normally at ground through the seat control switch. An individual motor is switched to voltage and ground when a specific adjustment position is selected.

Driver Power Seat With Memory

NOTE:
- A memory recall can be initiated only if the vehicle is in PARK or NEUTRAL gear and the ignition switch is not in START. A memory recall in progress will not be affected by moving the ignition switch to START or by moving the gearshift lever out of PARK or NEUTRAL.
- Verify good battery condition before diagnosing the memory seat system. Poor battery condition may interfere with memory seat operation, even if vehicle starting is possible.

The memory driver seat feature allows the driver to program a personalized seat position that can be recalled using the memory switch or a remote keyless entry (RKE) transmitter (if associated). There are 2 memory settings possible. The power adjustable pedals position is also stored and recalled with the power driver seat positions. For information on programming memory positions or recalling a stored memory position, refer to Memory Position Programming. Programming and Relearning

The driver power seat is controlled by the driver seat module (DSM), if equipped with memory seating. The DSM is located underneath the driver seat cushion frame. Programmable module installation (PMI) must be carried out when installing a new DSM. Refer to Information Bus (Module Communications Network). The DSM does not require calibration to the driver seat track.

The driver seat control switch provides voltage to the DSM when activated. The neutral position of each driver seat control switch position is a ground state through the seat control switch contacts. A voltage input causes the DSM to power the appropriate motor until the input is removed. Ground is the normal state of the motor circuits through the DSM and is not switched to control the motors. The DSM internally switches the appropriate circuit from ground to power for operating the motors.

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

The DSM communicates DTC and other information using the universal asynchronous receiver-transmitter (UART)-based protocol (UBP) communication bus. Refer to Information Bus (Module Communications Network) for additional information concerning UBP communication.

This section only diagnosis concerns specific to the memory seat. To diagnose a power adjustable pedal concern, refer to Brakes and Traction Control.

Remote Keyless Entry (RKE) Transmitter
A remote keyless entry (RKE) transmitter can be used to recall previously set memory positions but must first be associated to that memory position. The transmitter associated with personality 1 is capable of recalling memory position 1 only. Similarly, the associated personality 2 transmitter can recall only memory position 2.

Memory recall occurs when the unlock switch is depressed on the RKE transmitter if it has been associated with a memory position. The second depression of the unlock switch, which unlocks passenger doors, does not initiate a memory recall.

A memory recall in progress does not prohibit the initiation of another memory recall; the most recently requested memory recall will be executed. To associate a remote transmitter to a memory position, refer to Remote Keyless Entry Transmitter Programming in Locks. To diagnose a RKE transmitter concern, refer to Locks.

Easy Entry/Exit Feature
The easy entry/exit feature moves the seat backwards about 50.8 mm (2 in) when the ignition key is removed from the ignition switch. The DSM receives a key out command over the communication network and powers the driver seat rearward. This function will not operate if the seat is less than 50.8 mm (2 in) of travel distance from the end of the seat track or if the function has been disabled. The DSM will also cancel this operation if a valid input command is received, such as the seat control switch or memory recall request.

The DSM will record the current seat position before powering the seat for an easy exit operation. This recorded position will be used to return the seat to this position on the easy entry operation. During easy entry operation, the seat is returned to the position previous to the easy exit operation. Easy entry operation will be cancelled if a valid input command is received by the DSM.

The easy entry/exit feature can be enabled/disabled using a scan tool in Module Programming. When enabled, the feature becomes a user accessible item on the message center allowing the user to switch the feature on and off. The easy entry/exit feature is switched on and off by selecting EASY ENTRY on the message center display with the SETUP button and pressing the RESET button to select ON or OFF from the display menu. Refer to Driver Controls in the Owner's Literature or Instrument Panel, Gauges and Warning Indicators for additional instructions for using the message center.

Heated Seats

CAUTION:
- Do not install a new heater mat on a front passenger seat cushion. If a new cushion heater mat is needed on the front passenger seat, an occupant classification sensor (OCS) system service kit equipped with a heater mat must be installed. Failure to follow this instruction may result in incorrect operation of the OCS system. Refer to Air Bag Systems for the OCS removal and installation procedure.
- If installing a new cushion foam pad, the heater mat cannot be reused. A new heater mat must be installed. Failure to follow this instruction may result in component failure.

NOTE: A new heater mat can be attached to the foam pad where the old heater mat was removed but a used heater mat should not be reattached to any foam pad.

The driver and passenger heated seat modules share a common battery feed and ground source and have a separate ignition feed. The HVAC module includes the heated seat control buttons and indicators. The heated seat system will function when the HVAC module is ON or OFF. When a heated seat control button on the HVAC module is pressed with the ignition switch in RUN or START, a momentary ground signal is sent to the heated seat module. Upon receiving a signal, the heated seat module will decrease one setting (the sequence is HI, LO, OFF, HI, etc.). When a heated seat is set to HI, both indicators above the heated seat control button will illuminate. When a heated seat is set to LO, only the left indicator will illuminate. When a heated seat is set to OFF, neither indicator will be illuminated. Refer to Heating and Air Conditioning.

When the heated seat system is ON, the heated seat module then supplies power to the heater mat circuit. The cushion and backrest heater mats are wired in series and powered by the same output. The heated seat module will remain ON until the heated seat switch button is pressed to cycle the heated seat module to the OFF state or until the heated seat module automatically shuts off after 10 minutes. 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 heated seat switch button 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) in LO setting and 42°C (107.6°F) in HI setting and maintain the temperature until switched OFF or the 10 minute time out occurs. Temperature is maintained by the heated seat module which monitors the temperature sensor, located in the cushion heater mat, and adjusts the current flow to the heater mats.