Principles of Operation
Seats
Principles of Operation
Driver and Passenger Power Seats Without Memory
The driver and front passenger power seat uses a 6-way power seat track and 3 electric motors directly controlled by a seat-mounted seat control switch for horizontal (forward/rearward), front height and rear height adjustment. The driver seat can be equipped with a power recliner mechanism.
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 is not in START. A memory recall in progress will not be affected by the ignition being in START or by moving the gearshift lever out of PARK or NEUTRAL.
NOTE: 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 outside rear view mirror positions and power adjustable pedals position are 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. 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. The DSM does not require calibration to the driver seat track, however soft stops must be set.
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 motor position sensors to record the current seat position. The DSM will remove power 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 position sensor.
The DSM has the ability for soft stops both at the upper and lower limits on all axis of the driver seat. When an axis reaches the hard stop and the switch is held for approximately one second, it will then back up 180 milliseconds and establish the soft stop for that axis in that direction. The DSM uses this 'back up' strategy to check sensor integrity any time movement has stopped prematurely due to a sensor failure or obstruction.
The DSM communicates DTC and other information using the Medium Speed Controller Area Network (MS-CAN) communication bus. It should be noted for diagnostics that because Controller Area Network (CAN) bus communication is more robust and reliable than other methods, it may be possible to have limited module communication with one of the CAN bus circuits disconnected or shorted to ground. Refer to Information Bus for additional information concerning MS-CAN bus communication.
This only diagnoses concerns specific to the memory seat. To diagnose a memory power mirror concern, refer to Mirrors.
Driver Seat Module (DSM) Hard Stop/Soft Stop
A hard stop occurs when one of the memory seat track or backrest (recline) axes physically reach the end of travel and can go no further. A soft stop occurs when the seat stops before physically reaching the end of travel. The hard stop is set by seat design and cannot be changed or adjusted. The soft stop is set by the DSM. To prevent unnecessary stress on the seat, the DSM will set up to 10 soft stop positions, 2 for each moving axis. The seat track axes are forward/backward, front up/down and rear up/down. The seat backrest axis is forward/backward. The DSM will use a preset distance from the hard stop to determine where the soft stop will occur. When an axis reaches the hard stop and the switch is held for approximately one second, it will then back up 180 ms and establish the soft stop for that axis in that direction. The DSM uses this "back up" strategy to check sensor integrity any time movement has stopped prematurely due to a sensor failure or obstruction.
Remote Keyless Entry (RKE) Transmitter
A 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.
To associate a remote transmitter to a memory position, refer to Remote Keyless Entry (RKE) Programming in Locks. To diagnose a RKE transmitter concern, refer to Locks. Transmitter
Easy Entry/Exit Feature
The easy entry/exit feature moves the seat backwards about 2 mm (2 in) when the ignition key is removed from the ignition switch. The DSM receives a key out command over the MS-CAN communication network and powers the driver seat rearward. This function will not operate 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, when the ignition key is inserted into the ignition switch, 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 disabled and enabled on the message center display menu. Refer to Instrument Panel, Gauges and Warning Indicators or Owner's Literature for instructions for using the message center.
Heated Seats - Front
Vehicles equipped with front heated seats are equipped with a single-heated seat module to control both front heated seats. The heated seat module is located under the front passenger seat. The heated seat module does not time out. The system will function with the ignition in RUN, whether the engine is running or not. The heated seat module receives separate battery and ignition feeds and a ground source. The heated seat switches are part of the Front Controls Interface Module (FCIM). The heated seat system operates independently from the other systems controlled by the FCIM. When a heated seat control button on the FCIM is pressed, the Medium Speed Controller Area Network (MS-CAN) communicates the command to the HVAC module. The HVAC module then sends a momentary ground to the heated seat module to turn the heated seat on. Upon receiving a command, the heated seat module will decrease one setting (the sequence is high, low, off, high, etc.). When a heated seat is set to high, both LED indicators on the heated seat control button will illuminate. When a heated seat is set to low, only the lower LED indicator will illuminate. When a heated seat is set to off, neither LED will be illuminated.
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 control button is pressed to cycle the heated seat module off. If the ignition source is removed from the heated seat module, the heated seat module will enter an off state and will not return to on until the heated seat control button is once again pressed with the ignition in RUN. Temperature is maintained by the heated seat module, which monitors the temperature sensor in the cushion heater mat and adjusts the current flow to the heater mats.
Normal heat cycle may require several minutes to initially warm the seat. The seat should be occupied to correctly test for normal operation. Temperature measuring devices do not provide an accurate method for testing heated seat operation as surface temperatures are subject to human and environmental characteristics. Correct testing requires heater mat resistance measurements which have tight tolerances affecting the length of time for the heater mats to reach maximum operating temperature.
Heated seat module faults will only be detected when the module is operating in the LOW or HIGH state. If a fault is detected by the heated seat module, the module will stop supplying power to that individual left or right seat as well as the switch indicator on which that fault was detected. The faults detected will be: a heater feed circuit short to battery, ground or open; sensor circuit short to battery, ground or open; or heated seat switch stuck closed to ground. To reset the module, cycle the ignition OFF and then ON. After the heated seat module has been reset, the module will return to an off state. The heated seat module does not report DTCs and does not communicate on any communication network.
The heated seat module is designed with an auto-configuration feature for use on other vehicles with a heated seat system using a dual contact (dual throw) heated seat switch. This feature enables additional input circuits not intended for use on this vehicle and will cause the heated seats to operate incorrectly. If this occurs, the heated seats will both display a symptom of operating only in one mode and illuminating only one indicator. If this condition exists, a reset procedure is required to correctly configure the heated seat module for use. For diagnosis of this condition, GO to Symptom Chart. Symptom Related Diagnostic Procedures
Heated Seats - Rear
Vehicles equipped with rear heated seats are equipped with a single-heated seat module to control both rear heated seats. The heated seat module is located under the front console. The heated seat module does not time out. The system will function with the ignition in RUN, whether the engine is running or not. The heated seat module receives separate battery and ignition feeds and a ground source. The heated seat switches are part of the rear HVAC controls but the heated seat system operates independently from the climate control system. When a heated seat control button on the HVAC controls is pressed, 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 high, low, off, high, etc.). When a heated seat is set to high, both LED indicators on the heated seat control button will illuminate. When a heated seat is set to low, only the lower LED indicator will illuminate. When a heated seat is set to off, neither LED will be illuminated.
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 control button is pressed to cycle the heated seat module off. If the ignition source is removed from the heated seat module, the heated seat module will enter an off state and will not return to on until the heated seat control button is once again pressed with the ignition in RUN. Temperature is maintained by the heated seat module, which monitors the temperature sensor in the cushion heater mat and adjusts the current flow to the heater mats.
Normal heat cycle may require several minutes to initially warm the seat. The seat should be occupied to correctly test for normal operation. Temperature measuring devices do not provide an accurate method for testing heated seat operation as surface temperatures are subject to human and environmental characteristics. Correct testing requires heater mat resistance measurements which have tight tolerances affecting the length of time for the heater mats to reach maximum operating temperature.
Heated seat module faults will only be detected when the module is operating in the LOW or HIGH state. If a fault is detected by the heated seat module, the module will stop supplying power to that individual left or right seat as well as the switch indicator on which that fault was detected. The faults detected will be: a heater feed circuit short to battery, ground or open; sensor circuit short to battery, ground or open; or heated seat switch stuck closed to ground. To reset the module, cycle the ignition OFF and then ON. After the heated seat module has been reset, the module will return to an off state. The heated seat module does not report DTCs and does not communicate on any communication network.
The heated seat module is designed with an auto-configuration feature for use on other vehicles with a heated seat system using a dual contact (dual throw) heated seat switch. This feature enables additional input circuits not intended for use on this vehicle and will cause the heated seats to operate incorrectly. If this occurs, the heated seats will both display a symptom of operating only in one mode and illuminating only one indicator. If this condition exists, a reset procedure is required to correctly configure the heated seat module for use. For diagnosis of this condition, GO to Symptom Chart. Symptom Related Diagnostic Procedures
Second Row Power-Fold Seat
NOTE: The Smart Junction Box (SJB) may also be identified as Generic Electronic Module (GEM).
For the second row power-fold seat to operate, voltage is supplied by the SJB to the power-fold seat relay, enabling the seats to then be moved by pressing the second row power-fold seat switch.
The power-fold seat relay will be provided voltage on the coil side from the SJB for 30 minutes when the transmission selector is in PARK, and the liftgate, or liftgate glass, is open. The voltage will be disabled 30 minutes after turning the vehicle OFF. If the relay is disabled after 30 minutes, it can be enabled by opening any door, pressing the unlock key on the key fob, pressing any keyless keypad button or turning the ignition key.
The second row power-fold seat motor retracts a cable to release the backrest recliner latches and allows the backrest assist spring to fold the backrest forward onto the seat cushion. The power-fold seat motor continues to retract to release the seat-to floor latches and allows the spring assist strut to lift and tumble the seat forward to the E-Z entry position for 3rd row seat access. Immediately after the seat is fully released, the power-fold seat motor returns the release cable and latches to a relaxed state, ready for manual latching. To return to a seating position, the seat must be manually latched to the floor and the backrest must be manually latched upright.
Second Row 60/40 Percent E-Z Entry Seats
NOTICE: The backrest must be folded flat (fully downward) before the floor latches can be released. Make sure there are no objects on the seat before lowering the backrest(s). Failure to follow this instruction may cause damage or incorrect operation of the seat.
The 60/40 E-Z entry seats have the following 3 functional positions:
- Backrest fold-flat
- E-Z entry (fold-forward position for third row access)
- Upright
For backrest fold-flat position, lower the head restraint, pull the release strap or recliner handle up and fold the backrest fully downward. To return upright (seating position), pivot and raise the backrest toward the rear of the vehicle until locked upright (vertical) for occupancy.
For E-Z entry, move the backrest to the fold-flat position and pull the release strap or recliner handle a second time to release the floor latches. Lift up on the rear of the seat, pivoting it forward, away from the third row seats and up to the E-Z entry position. To return the seat, push the rear of the seat down with moderate force to latch the seat to the strikers. Make sure the seat is latched to the strikers by lifting up on the rear of the seat. Lift and pivot the top of the backrest toward the rear of the vehicle, rotating the backrest until a click is heard, locking it in the upright position. Make sure the seat backrest is locked in position.
For access to the third row seats through the rear doors, fold the seat up out of the way (E-Z entry position), after the backrest has been folded down. To release the latch feet from the strikers and position the seat to the E-Z entry position, the backrest must be folded forward and all the way down. Remove anything between the backrest and cushion that may prevent the backrest from folding all the way down.