Principles Of Operation

Seats

Principles of Operation

Driver and Passenger Power Seats Without Memory

The 10-way seat control feature moves the seat in 10 possible directions: the seat can be moved forward or backward and the front and back of the cushion can be moved up and down independently. The backrest of the seat can be moved forward and backward, and the lumbar can be moved in and out. All 10 positions are controlled by one switch. The power seat feature operates independent of the ignition position.

The 6-way power seat feature moves the seat in 6 possible directions: the seat can be moved forward or backward and the front and back of the cushion can be moved up and down independently. The power seat feature operates independent of the ignition position.

The power seat motors are hardwired to the seat control switch. The circuits are normally at ground through the seat control switch. An individual circuit is switched to voltage when a specific adjustment position is selected.

Power Driver Seat With Memory

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.

NOTE: A memory recall in progress does not prohibit the initiation of another memory recall; the most recently requested memory recall will be executed.

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 exterior mirrors, power adjustable pedal (if equipped) and power steering column (if equipped) positions are also stored and recalled with the power driver seat positions. The power steering column memory positioning is only used to raise the column upon easy exit and position it back upon easy entry.

The Driver Seat Module (DSM) does not require calibration to the driver seat track, although soft stops must be set within the seat track physical limits.

The driver seat control switch provides voltage to the DSM (Driver Seat Module) 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 (Driver Seat Module) to power the appropriate motor until the input is removed. Ground is the normal state of the motor circuits through the DSM (Driver Seat Module) and is not switched to control the motors. The DSM (Driver Seat Module) internally switches the appropriate circuit from ground to voltage for operating the motors.

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

The DSM (Driver Seat Module) communicates DTCs and other information using the MS-CAN (Medium Speed Controller Area Network) 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 (Controller Area Network) bus circuits disconnected or shorted to ground. for information concerning MS-CAN (Medium Speed Controller Area Network) bus communication.

This system only diagnoses concerns specific to the memory seat. To diagnose an exterior mirror concern, refer to Mirrors. To diagnose a power adjustable pedal concern, refer to Hydraulic System, Brakes &/or Brake Pedal Assy. To diagnose a power steering column concern, refer to Steering Column.

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

Easy Entry/Exit Feature

The easy entry/exit feature is a function of the DSM (Driver Seat Module) that moves the driver seat backwards about 51 mm (2 in) and the power steering column (if equipped) to the full upward position when the ignition key is removed from the ignition switch. The DSM (Driver Seat Module) receives a key out command over the MS-CAN (Medium Speed Controller Area Network) and powers the driver seat rearward and the steering column upward. This function will not operate if the seat is less than the 51 mm (2 in) travel distance to the end of the track or the function has been disabled. The DSM (Driver Seat Module) will also cancel this operation if a valid input command is received from the driver seat control switch, memory SET switch, adjustable pedal control switch, exterior mirror control switch or power steering column switch.

The DSM (Driver Seat Module) will record the current seat and power steering column (if equipped) positions before powering the seat and column for an easy exit operation. This recorded position will be used to return the seat and steering column to this position on the easy entry operation. During easy entry operation, the seat and steering column are 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 (Driver Seat Module).

The easy entry/exit feature can be enabled/disabled using a scan tool. When enabled, the feature becomes a user accessible item on the message center allowing the user to turn the feature on and off. Refer to the Owner's Literature or Instrument Panel, Gauges and Warning Indicators for information on the message center.

Remote Keyless Entry (RKE) Transmitter

NOTE: A memory recall in progress does not prohibit the initiation of another memory recall; the most recently requested memory recall will be executed.

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 (Remote Keyless Entry) 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.

For information on diagnosing an RKE (Remote Keyless Entry) concern or associating a RKE (Remote Keyless Entry) transmitter to a memory position, refer to Doors, Hood and Trunk &/or Locks.

Driver Seat Module (DSM) Hard Stop/Soft Stop

A hard stop occurs when one of the memory seat track, backrest (recline) or power steering column axes physically reach the end of travel and can go no further. A soft stop occurs when the seat or steering column stops before physically reaching the end of travel. The hard stop is set by seat or steering column design and cannot be changed or adjusted. The soft stop is set by the DSM (Driver Seat Module). The seat track axes are forward/rearward, front up/down and rear up/down. The seat backrest axis is forward/rearward and the steering column axis is up/down. To prevent unnecessary stress on the seat, steering column and motors, the DSM (Driver Seat Module) will set up to 10 soft stop positions, 2 for each moving axis. The DSM (Driver Seat Module) 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 milliseconds and establish the soft stop for that axis in that direction. The DSM (Driver Seat Module) uses this "back up" strategy to check sensor integrity any time movement has stopped prematurely due to a sensor failure or obstruction.

Setting the Soft Stop

NOTE: If a new DSM (Driver Seat Module) has been installed, all power driver seat and power steering column (if equipped) soft stops must be reset. If a new seat track, recline motor or power column has been installed, only reset the soft stops for that component being installed new.

Use the following procedure once a new seat track, recline motor, power steering column or DSM (Driver Seat Module) has been installed.

During the setting procedure, one second after a seat track, seat backrest or steering column axis reaches its end of travel in either direction, the DSM (Driver Seat Module) will move the motor being used on that particular axis a small amount in the opposite direction of the way the switch is being pressed. Once the motor has moved the seat track or backrest this small amount, the soft stop is set and the switch can be released.

1. Turn the ignition key to the ON position.

2. Press the seat control switch horizontal button forward until the seat track stops.

3. Keep the horizontal button pressed forward for one second after the seat track reaches its forward end of travel. The seat track will then move back a small amount. The horizontal forward soft stop has been set, release the switch button.

4. Repeat Steps 2 and 3 for all seat track and backrest axes in both directions.

5. Repeat Steps 2 and 3 for power column (if equipped).

Climate Controlled Seat System

NOTICE: Avoid applying voltage directly to a Thermo-Electric Device (TED) for testing its operation. Doing so may cause damage to the TED (Thermo-Electric Device).

NOTE: When installing a new Dual Climate Controlled Seat Module (DCSM), it is necessary to carry out Programmable Module Installation (PMI). Programming and Relearning Refer to Information Bus.

Both the driver and front passenger climate controlled seats are independently controlled electronically by the DCSM (Dual Climate Controlled Seat Module) mounted to the bottom of the passenger seat cushion. The climate controlled seat system only operates with the engine running, however, if using a scan tool to command the DCSM (Dual Climate Controlled Seat Module), diagnostic testing can be carried out with the ignition ON engine OFF in 15 second durations. The system receives voltage from Battery Junction Box (BJB) fuse 67 (40A) supplying battery voltage into the DCSM (Dual Climate Controlled Seat Module).

If one of the voltage supply circuits opens, both seats will remain operational because the circuits are connected internally in the DCSM (Dual Climate Controlled Seat Module).

Both climate controlled seats operate independently. If a fault occurs setting a DTC specific to either climate controlled seat, only the affected seat will be disabled by the module. If the system shuts down due to a DTC fault, cycling the ignition to OFF and then ON again will reset the DCSM (Dual Climate Controlled Seat Module) to function until the DTC resets.

The 4 climate controlled seat switches (identified with seat icons) on the HVAC module activate each seat system setting and illuminate indicators above each switch to indicate the operating mode. There are 3 indicators for HIGH, 2 indicators for MED and 1 indicator for LOW.

Each driver and front passenger seat cushion and backrest is equipped with a Thermo-Electric Device (TED) and blower motor assembly. Applying voltage polarity to the TED (Thermo-Electric Device) in one direction, causes it to heat. Applying voltage polarity in the opposite direction causes the TED (Thermo-Electric Device) to cool. Cabin air is drawn through the blower and distributed to each of the TED (Thermo-Electric Device) modules located in the seat cushion and backrest. The TEDs (Thermo-Electric Devices) then heat or cool the incoming air depending on the control switch settings. The air is then directed into the foam pad and manifold where it is distributed along the surface of the cushion and backrest of the seat. Once activated, the DCSM (Dual Climate Controlled Seat Module) maintains the heating/cooling modes until deactivated.

The temperature differences between the individual heated and cooled settings is minimal. For example, it is difficult to distinguish between LOW cool and MED cool settings. Measuring seat temperature at different settings is possible by monitoring the DCSM (Dual Climate Controlled Seat Module) PIDs using the scan tool.

The HVAC module communicates climate controlled seat commands to the DCSM (Dual Climate Controlled Seat Module) using the MS-CAN (Medium Speed Controller Area Network) bus. The MS-CAN (Medium Speed Controller Area Network) bus is connected to the Data Link Connector (DLC) for diagnostic use. No direct connection exists between the DCSM (Dual Climate Controlled Seat Module) and HVAC module for the climate controlled seat switches. The climate controlled seats can be commanded on or off using the scan tool to verify both module communication on the MS-CAN (Medium Speed Controller Area Network) bus and operation of the DCSM (Dual Climate Controlled Seat Module). This method may be useful for isolating a control switch concern. It should also be noted that because CAN (Controller Area Network) bus communication is more robust and reliable than other methods, it may be possible to have limited module communication with one of the CAN (Controller Area Network) bus circuits disconnected or shorted to ground. Refer to Information Bus for information concerning CAN (Controller Area Network) bus communication.

Heating Characteristics

- In heat mode, the TED (Thermo-Electric Device) circuits of a given seat are wired in parallel internally in the DCSM (Dual Climate Controlled Seat Module).

- The climate controlled seat system draws approximately 24 amperes, with both seats heating, until reaching the set point and then the system operates at a reduced amperage to maintain the climate setting.

- In heat mode, the TED (Thermo-Electric Device) can add up to 40°C-60°C (72°F-108°F) to the ambient inlet air temperature as it passes over the TED (Thermo-Electric Device).

- The system control settings are based on the indicators above each climate controlled seat heat switch button on the HVAC module.

- In the LOW setting, the DCSM (Dual Climate Controlled Seat Module) is set to maintain TED (Thermo-Electric Device) temperature at approximately 46°C (115°F).

- In the HIGH setting, the DCSM (Dual Climate Controlled Seat Module) is set to maintain TED (Thermo-Electric Device) temperature at 65°C (149°F).

- When heating, the DCSM (Dual Climate Controlled Seat Module) will vary the speed of the fans and the TED (Thermo-Electric Device) duty cycle in order to reach and maintain the temperature determined by the switch setting (closed loop operation). Refer to the following table for heating mode temperatures.





Cooling Characteristics

- In cool mode, the TED (Thermo-Electric Device) circuits of a given seat are wired in series internally in the DCSM (Dual Climate Controlled Seat Module).

- The climate controlled seat system draws approximately 7 amps.

- In cool mode, the TED (Thermo-Electric Device) can remove up to 8°C (14°F) from the ambient air temperature entering the system.

- The system control settings are based on the indicators above each climate controlled seat cool switch button on the HVAC module.

- When cooling, the DCSM (Dual Climate Controlled Seat Module) maintains constant speed of the fans and constant TED (Thermo-Electric Device) supply voltage (duty cycle) in open loop COOL mode (refer to the following table).





The climate controlled seat system is deactivated by one of the following actions:

- Selecting the HVAC module setting to manual OFF

- Turning the vehicle OFF

If the temperature at one of the TEDs (Thermo-Electric Devices) falls below 5°C (41°F), the DCSM (Dual Climate Controlled Seat Module) will shut down the TEDs (Thermo-Electric Devices) and initiate system recovery mode. If the temperature continues to drop below 2°C (36°F), the DCSM (Dual Climate Controlled Seat Module) will shut down the fans in the affected seat.

Climate Controlled Seat System Recovery Mode

NOTE: The presence of overtemperature faults (DTCs B2729, B2730, B272A and B272B) can be induced by incorrect operation of the climate controlled seat system after an initial heat setting has been attained. If a heat setting is repeatedly turned OFF and ON in an attempt to increase the seat temperature or repeatedly toggled between heat and cool modes, an overtemperature condition can result and the DTC(s) will be set.

If the temperature at one of the TEDs (Thermo-Electric Devices) rises above 110°C (230°F) in the heat mode or 65°C (149°F) in the cool mode for more than 4 seconds, the DCSM (Dual Climate Controlled Seat Module) will record an overtemperature DTC, remove voltage from the TEDs (Thermo-Electric Devices) and go into recovery mode (blower only) for 30 seconds to cool down the TEDs (Thermo-Electric Devices). The same will occur if a temperature difference of 60°C (108°F) or greater is seen between the backrest and cushion TEDs (Thermo-Electric Devices) on either front seat. The DCSM (Dual Climate Controlled Seat Module) will continue to monitor the TEDs (Thermo-Electric Devices) while in recovery mode. If the temperature of the TEDs (Thermo-Electric Devices) does not drop to 105°C (221°F) in the heat mode or 60°C (140°F) in the cool mode after 30 seconds, the system will continue to cool the TEDs (Thermo-Electric Devices) in recovery mode for up to 5 minutes. If the TEDs (Thermo-Electric Devices) cool down at anytime after 30 seconds, but before 5 minutes (checked at 4-second intervals), the system will operate as normal. An overtemperature DTC will still be recorded even if the system recovers and is operating normally. This scenario is more likely to occur during extreme cabin temperatures with significant seat back sunload. If the system does not recover within 30 seconds in heat mode or within 5 minutes in cool mode, the DCSM (Dual Climate Controlled Seat Module) will disable that seat (fault mode) and remain off until the ignition is cycled. Also, if the DCSM (Dual Climate Controlled Seat Module) detects temperature differential fault twice during the same ignition cycle, it will shutdown. When a fault causes a shutdown the climate controlled seat indicators will turn off and that seat will not be operational until the next key cycle.

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 floor console. When the heated seat switch is pressed, a momentary ground signal is sent to the heated seat module. The heated seat module then supplies voltage to the heater circuit. The seat cushion and backrest heater mats are wired in series and supplied voltage by the same output. The heated seat module monitors inputs from a temperature sensor, located in each seat's cushion heater mat and maintains seat temperature by cycling the heater feed output as necessary to maintain the set point temperature. The heated seat module will send voltage to the indicator circuit at the heated seat switch to indicate an on state. The heated seat module will remain on until the heated seat switch is pressed to supply a second momentary ground signal or the ignition is set to OFF. The heated seat module does not time out.

The heated seat module does not report DTCs and does not communicate on any network. If a fault is detected the affected seat system will be disabled. The faults detected will be:

- a heater feed circuit short to battery, ground or open.

- sensor circuit short to battery or open.

- heated seat switch stuck closed to ground.

- heated seat switch low and high inputs shorted together.

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.

A new heated seat module must be configured after installation for correct operation. Heated seat module configuration occurs automatically when the low heat mode button is pressed on either rear heated seat switch. Until the module is correctly configured, the heated seats will operate incorrectly from the high heat mode button on either heated seat switch by following a sequence of high, low and off with each button press. After the low heat mode button is pressed on either heated seat switch, the module will correctly configure and the system will operate correctly.

Third Row Power-Fold Seat

NOTICE: To prevent possible damage to the third row seat or the safety belts, make sure that the safety belts are not fastened when moving the seat to the load floor position.

NOTICE: Make sure that no objects such as books, purses or briefcases are on the floor in front of the third row seats or on the seat cushion before lowering the backrest(s). Failure to follow this instruction may cause incorrect operation of the seat.

NOTE: The Smart Junction Box (SJB) may also be identified as the Generic Electronic Module (GEM).

For the third row power-fold seat to operate, voltage is supplied by the SJB (Smart Junction Box) to the power-fold seat relay, enabling the seats to then be moved by pressing the third row power-fold seat switches. The third row power-fold seat operates only when the vehicle is in PARK and the liftgate glass, liftgate door or any entry door must be open.

The third row power-fold seat motors transfer movement to a drive gear assembly to raise and lower the seat backrest. The power-fold seat motors rotate a short torque shaft which is connected to the drive gear assembly. The power-fold seat motor and bracket assembly is serviceable separately. Refer to Power-Fold Seat Motor .