Ford Explorer: Second Row Seats / Description and Operation - Second Row Seats - System Operation and Component Description

Ford Explorer 2020-2021 Service Manual / Body and Paint / Body and Paint / Second Row Seats / Description and Operation - Second Row Seats - System Operation and Component Description

System Operation

System Diagram - Heated/Ventilated Seats


Item Description
1 RHVAC
2 MS-CAN
3 SCMF
4 LH Second Row Seat
5 Cushion Temperature Sensor
6 RH Second Row Seat
7 Backrest Heater Mat
8 Cushion Heater Mat
9 Cushion and Backrest Blower Motors
10 Backrest Heater Mat
11 Cushion Heater Mat
12 Cushion Temperature Sensor
13 Cushion and Backrest Blower Motors

Network Message Chart - Heated/Ventilated Seats

  SCMF (rear seat climate control module) Network Input Messages


Broadcast Message Originating Module Message Purpose
Seat control requests RHVAC control module Contains the heated/ventilated seat request information.

  RHVAC Control Module Network Input Messages


Broadcast Message Originating Module Message Purpose
Seat control button status SCMF (rear seat climate control module) The SCMF (rear seat climate control module) provides this message to the RHVAC control module for the purpose of updating the displayed status of the seat control buttons on the RHVAC module.

Power-Fold Down Backrest

When activated, the second row single seat easy entry seat fold switch supplies a momentary ground signal to the SCMJ. When the SCMJ receives the switch input, it supplies power and ground to the second row easy entry power release actuator to retract the second row easy entry power release cable (connected to the same seat mechanism as the manual release pull strap) that releases the backrest recliner latches, allowing the backrest assist spring to fold the backrest forward. The second row easy entry power release actuator continues to release the seat-to-floor latches to allow the assist spring to move the seat forward to the easy entry position for third row seat access. Immediately after the seat is fully released, the second row easy entry power release actuator returns the second row easy entry power 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.

Rear Heated Seats

The heated seats are controlled by the heated second row seat module located under the RH second row seat cushion frame. When the heated seat switch (part of the RHVAC module) is pressed, a momentary ground signal is sent to the heated second row seat module to supply voltage to the heater circuit. When the heated seat feature is active, the heated second row seat module supplies voltage to the heater circuit. The seat cushion and backrest heater mats are wired in series. The heated second row seat module monitors input from a temperature sensor located in each backrest heater mat and maintains seat temperature by cycling output voltage to the heater grids as necessary to maintain the setpoint temperature. The heated second row seat module supplies voltage to the RHVAC module assembly to illuminate the appropriate indicator circuit(s) in the heated seat switch when the system is active. In high mode, both indicators on the heated seat switch illuminate. In low mode, only the low indicator illuminates. The heated second row seat module does not time out and remains on until switched off or ignition is off.

The heated second row seat module does not report Diagnostic Trouble Codes (DTCs) and does not communicate on any network. If a fault is detected, the affected seat system is disabled. The faults detected are:

  • a heater feed circuit short to battery, ground or open.
  • sensor circuit short to battery or open.
  • heated seat switch stuck closed to ground.

After the fault is corrected, reset the heated second row seat module by cycling the ignition OFF and then ON. After the heated second row seat module has been reset, the module returns to an off state.

Heated/Ventilated Seats

The driver and passenger heated/ventilated seat buttons are selected from the RHVAC module. When a switch is activated, a message is sent from the RHVAC module to the SCMF over the MS-CAN. The heated/ventilated seat system functions independently from the vehicle's climate control system.

Heated Operation

  • The system control settings are indicated on each heated/ventilated seat switch button. The first setting is HIGH (3 indicators), the second setting is MED (2 indicators) and the third is LOW (1 indicator) then OFF (no indicators).
  • When activated, the SCMF supplies voltage to the selected seat heater circuit. Each seat cushion heater mat and backrest heater mat is connected in a series circuit to the SCMF and powered by the output circuit for that seat. The SCMF monitors inputs from a temperature sensor located in each seat cushion heater mat, and maintains seat temperature by cycling the heater circuits on/off. The heated seat remains on until the heated seat switch button is pressed to cycle the SCMF OFF or the ignition is set to off.

Ventilation Operation

  • The seat cushion and backrest are each equipped with a blower motor assembly. Each blower motor draws air through the surface of the cushion and backrest through the foam. Once the system is activated, the SCMF controls the blower speed dependant on the heated/ventilated seat settings.
  • The system control settings are based on the 3 indicators on each heated/ventilated seat switch button. The first setting is HIGH (3 indicators), the second setting is MED (2 indicators) and the third is LOW (1 indicator) then OFF (no indicators).

Component Description

Second Row Single Seat Easy Entry Seat Fold Switch

The second row single seat easy entry seat fold switch is a momentary contact switch that, when pressed, supplies a ground input to the SCMJ to fold the backrest forward.

Second Row Easy Entry Power Release Actuator

The second row easy entry power release actuators release a locking mechanism allowing the seat backrest to fold down onto the seat cushion. When the LH or RH second row single seat easy entry seat fold switch is activated, voltage is applied to operate the associated actuator. The second row easy entry power release actuators contain internal switching that operate the actuator until it moves to the reset position and turns off.

Second Row Easy Entry Power Release Cable

When the SCMJ receives the switch input, it supplies power and ground to the second row easy entry power release actuator to retract the second row easy entry power release cable (connected to the same seat mechanism as the manual release pull strap) that releases the backrest recliner latches, allowing the backrest assist spring to fold the backrest forward.

RHVAC Module

The RHVAC module contains the heated seat switches or heated/ventilated seat control switches.

Heated Second Row Seat Module

When commanded by the heated seat switch, the heated second row seat module monitors the appropriate seat backrest temperature sensor(s) and supplies heater current to the seat cushion and backrest heater mats until the desired setpoint temperature is reached. Once the setpoint temperature is reached, the heated second row seat module cycles the heater circuits on/off as required to maintain the setpoint temperature. The heated second row seat module does not report Diagnostic Trouble Codes (DTCs) and does not communicate on any network. If the heated second row seat module detects a fault, the affected seat system is disabled.

SCMF

The SCMF controls the operation of the heated/ventilated seat system. PMI is required when a new SCMF is installed.

SCMJ

The SCMJ controls the operation of the second row easy entry power release actuators. PMI is required when a new SCMJ is installed.

Seat Heater Mat

Each seat backrest heater mat is equipped with a temperature sensor (thermistor) which provides feedback to the heated second row seat module (heated seats only) or SCMF (heated/ventilated seats only). The cushion and backrest heater mats are connected in series.

Blower Motor

If equipped with heated/ventilated seats, the seat cushion and backrest are each equipped with a blower motor assembly. The blower motor assembly is controlled by the SCMF.

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