Principles of Operation

PRINCIPLES OF OPERATION

Driver Power Seat
The driver power seat motors are hardwired to the driver seat control switch. The circuits are normally at ground through the seat control switch. The individual circuit is switched to power when the specific adjustment position is selected.

Driver Power Seat - Memory

NOTE: Before carrying out diagnostic testing for the driver seat module (DSM) wake the module by activating the power seat using the power seat switch, otherwise module communication failure will occur.

The driver power seat is controlled by the driver seat module (DSM). The DSM does not need to be configured, however the driver seat does need to be calibrated when the DSM is installed. 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 line from ground to power 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 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 must be calibrated to the seat track it is controlling. Once the DSM is calibrated to the seat track, it will only allow movement within the calibrated range.

Seat Calibration
The DSM is calibrated using a diagnostic tool. The calibration procedure automatically powers the driver power seat through its full range of motion and records the full stop positions by monitoring the motor position sensors. Once the full stop positions or range of the seat have been recorded, the DSM will only operate within the calibrated range. Any input 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.

Passenger Power Seat
The passenger power seat motors are hardwired to the passenger seat control switch. The circuits are normally at ground through the seat control switch. The individual circuit is switched to power when the specific adjustment position is selected.

Heated Seats
The driver and passenger heated seat modules share a common battery feed and ground source and have a separate ignition feed. The dual automatic temperature control (DATC) module includes the heated seat control buttons and indicators. The heated seat system will function when the DATC module is ON or OFF. When a heated seat control button on the DATC 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 1 setting (the sequence is HI, LO, OFF, HI, etc.). When a heated seat is set to HI, both LED indicators above the heated seat control button will illuminate. When a heated seat is set to LO, only the left 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 heating element circuit. The cushion element and backrest element 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 to the OFF state. 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 control 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. 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.

Climate Controlled Seat System
The climate controlled seat system is able to heat and cool the front seats. Each climate controlled front seat is controlled by buttons located on the dual automatic temperature control (DATC) module.

Both the driver and front passenger seat has an independent climate controlled seat system installed. A climate controlled seat module mounted to the bottom of the seat cushion electronically controls the climate controlled seat system. The climate controlled seat system receives power from both the battery power and vehicle run circuits. The vehicle must have ignition ON and the dual automatic temperature control (DATC) module switch set to HEAT or COOL 1, 2, 3 or AUTO for the climate controlled seat system to activate.

AUTO mode is achieved by pressing the HEAT and COOL settings simultaneously. The center LED will be illuminated when the CCSM is in AUTO mode.

Cabin air is drawn through the seat fan motor and distributed to each of the thermo-electric device (TED) modules located in the seat cushion and backrest. The TEDs then heat or cool the air. The air is then directed into the foam pad B-surface. Channels in the A-surface of the foam pad are used to distribute the air along the surface of the seat.

The TED uses a "Peltier" circuit of P-type and N-type semiconductors connected in series using copper electrical conductors. The semiconductors are sandwiched between 2 insulating ceramic plates. When current is applied to the TED, 1 side releases energy as heat, while the opposite side absorbs energy and gets cold. By reversing the current flow, the hot and cold sides reverse.

The temperature differences between the individual HEAT and COOL settings is minimal. For example, it is difficult to distinguish between LOW COOL and MEDIUM COOL settings. Monitoring the seat temperature at different HEAT or COOL settings should not be done as it is ineffective in confirming climate controlled seat system operation.

Heating Characteristics

NOTE: The presence of overtemp faults (DTCs B2729 and B2730) 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, an overtemp condition can result and the DTC(s) will be set.
- The climate controlled seat system draws approximately 7.5 amps until reaching the set point and then the system draws approximately 2 amps to maintain the climate setting.
- In HEAT mode, the TED can add up to 40-60°C (72-108°F) to the ambient air temperature entering the system.
- There are 3 manual settings based on the position of the climate controlled seat switch on the DATC module. Position 1 is the LOW setting and position 3 is the HIGH setting.
- There are 5 AUTO HEAT settings. The AUTO HEAT setting is determined by the temperature setting of the DATC module when the CCSM is in AUTO HEAT mode.
- In the LOW setting, the climate controlled seat Thermomodule is set to maintain TED temperature at 37°C (99°F).
- In the HIGH setting, the climate controlled seat module is set to maintain TED temperature at 65°C (149°F).
- If the temperature at 1 of the TEDs rises above 85°C (185°F) in the HEAT mode or 70°C (149°F) in the COOL mode for more than 4 seconds, the CCSM will record an overtemp DTC, remove power from the TEDs and go into Blower Only mode in an attempt to cool down the TEDs. If the TED temperature has not dropped to 80°C (176°F) in the HEAT mode or 65°C (140°F) in the COOL mode after 30 seconds, the CCSM will shut down and remain off until the ignition is cycled. Also if the CCSM detects an overtemp twice during the same ignition cycle, it will also shut down.
- In HEAT mode, there is no linear correlation between the (DATC) module, the seat fan motor speed and the TED supply voltage. The CCSM will independently vary the fan speed and the TED supply voltage in order to reach and maintain the temperature determined by the (DATC) module setting.

Cooling Characteristics
- The climate controlled seat system draws approximately 4.5 amps for the first 12 minutes and will operate at 2 amps thereafter.
- In COOL mode, the TED can remove up to 8°C (14°F) from the ambient air temperature entering the system.
- There are 3 manual settings based on the position of the climate controlled seat switch on the DATC module. Position 1 is the LOW setting and position 3 is the HIGH setting.
- If the temperature at 1 of the TEDs goes below 18°C (64°F), the climate controlled seat module will shut down the TEDs. If the temperature continues to drop below 12°C (54°F), the climate controlled seat module will shut down the fan motor.
- In COOL mode, there is a correlation between the seat fan motor speed and the TED supply voltage.

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Part 2:

The climate controlled seat system is deactivated by 1 of the following actions:
- Setting the DATC module setting to manual OFF.
- Turning the vehicle off.