Principles of Operation (How Does It Work?)

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: The memory power seat track may stall when operating at 0°C (32°F) or below. Once the vehicle's interior temperature rises above 0°C (32°F), normal operation should return.

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 scan 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.

The calibration procedure powers the seat track adjustments to the end of their travel, which is determined by the DSM sensing a change of state in the motor position sensors. If there is a concern with the seat track or motor position sensor that limits the 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.

For additional information on carrying out the power seat calibration procedure, refer to the scan tool operating manual.

Memory Seat
Memory seat positioning can be recalled with the memory switches on the driver door panel or a programmed remote keyless entry transmitter. In either case, the DSM receives a memory recall 1 or 2 command from the driver door module (DDM) over the SCP communication network. The memory recall switches are a hardwired input to the DDM. The DDM also receives the remote keyless entry transmitter signals. Once a valid memory recall command is received from the DDM, the DSM moves the driver seat to the position stored in memory by powering the appropriate motors and monitoring the motor position sensors until the position is reached.

This system allows automatic positioning of the driver seat to two programmable positions.
- To program position one, move the driver seat to the desired position using the seat control switch. Depress the set button. Within five seconds, depress button one.
- To program position two, repeat the previous procedure using the set button and button two.
- To recall position one, depress button one. To recall position two, depress button two.

A position can only be recalled when the transmission selector is in PARK or NEUTRAL. A position may be programmed at any time.

Easy Exit/Easy Entry
The easy exit function moves the seat backwards about two inches when the ignition key is removed from the ignition switch. The DSM receives a key out command over the SCP communication network and powers the driver seat rearward. This function will not operate if the seat is less than the travel distance to the end of the track, or the function has been deactivated at the message center driver personality settings. 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 function. 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.

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.

Climate Controlled Seat System
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 unit (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.

Once the system is activated, the climate controlled seat module uses a set of flexible algorithms to control the heating/cooling modes, and the fan motor speed based on the climate controlled seat switch settings. These algorithms are designed to protect the user from potentially harmful prolonged exposure to climate extremes.

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 two insulating ceramic plates. When current is applied to the TED, one 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 over-temp 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 over-temp 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 three manual settings based on the position of the climate controlled seat switch on the DATC module. Position one is the LOW setting and position three is the HIGH setting.
- There are five 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 module 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 one 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 four 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 TEDs 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 seven amps until reaching the set point, and then the system draws approximately two amps to maintain the temperature setting.
- In the COOL mode, the TED can remove up to 8-10°C (14-18°F) from the ambient air temperature entering the system.
- There are three manual settings based on the position of the climate controlled seat switch on the DATC module. Position one is the LOW setting and position three is the HIGH setting.
- If the temperature at one of the TEDs falls 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 DATC module, the seat fan motor speed and the TED supply voltage. Fan supply voltage is used in the following equation (seat fan motor supply voltage/0.74 x ignition voltage) to determine the fan duty cycle. For additional information refer to the chart.

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

Rear Heated Seats
The left and right rear heated seats share a common battery and ignition feed. A separate shared ground source supplies the heated seat switches. When the heated seat switch is pressed with the ignition switch in RUN, a momentary ground 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 will also provide voltage to the separate 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 and a momentary ground 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 timed-out or 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.

Occupant Classification Sensor

CAUTION:
- If installing only the front passenger seat cushion trim cover, the seat occupant classification sensor (OCS) must be rezeroed.
- The following precautions must be taken before rezeroing of the OCS system.
- Make sure the OCS system components are connected and no faults are present.
- Make sure the vehicle has not been exposed to temperatures below 6°C (42°F) or above 36°C (97°F) within four hours prior to the rezeroing process. If the vehicle has been exposed to temperatures outside the temperature limits (6-36°C), the vehicle must be exposed to and kept at a temperature within the limits for minimum of four hours.
- Make sure nothing is present on the passenger seat before rezeroing and nothing is placed on the seat during the rezeroing process.
- Make sure a minimum five second time period has passed after cycling the ignition switch ON before the rezeroing process.

NOTE:
- It is necessary to rezero the OCS system when a front passenger seat cushion is disassembled, a new trim cover installed, or an OCS service kit is installed. A scan tool is used to trigger the active command to carry out rezeroing of the OCS system.
- When using a New Generation Star (NOS) tester, the OCS system rezero function is on the Ford Service Function (red) card. To rezero the OCS system:
- select "SERVICE BAY FUNCTIONS"
- select "RCM"
- select "SYSTEM RESET"
- select the vehicle from the menu
- view the on-screen information then press "TRIGGER"

The NGS screen will then display "OCS RESET: REZERO." Press "DONE" (button 8) to rezero the OCS system. The NGS will return to the vehicle menu once rezeroing of the OCS system is complete.

NOTE: To rezero the OCS system using the Worldwide Diagnostic System (WDS):
- select the "Toolbox" icon
- select "Body" from the menu
- select "Restraints" from the menu
- select "Seat Weight Sensor ReZero"

After selecting "Seat Weight Sensor ReZero", follow the on-screen prompts to carry out rezeroing of the OCS system.

NOTE: If the first attempt to rezero the OCS system is unsuccessful, a second attempt must be made.

The seat occupant classification sensor system is found only on the front passenger seat. The OCS system components (seat cushion foam pad, bladder, bladder with pressure sensor and electronic control unit) are calibrated to each other and are serviced as an assembly. OCS system components are not to be installed separately. If installing a new OCS system, OCS system component or seat cushion foam pad, a new OCS system service kit (seat cushion foam pad, bladder, bladder with pressure sensor and electronic control unit) must be installed as an assembly.