Seat Heater System: Inspection

2004 Toyota Matrix XR, FWD, StandardSECTION Inspection
WARNING: This page is about a different car, the 2004 Lexus ES 330. However, it is still accessible from the selected car via links, so may be relevant.
  1. INSPECT FRONT SEAT CUSHION HEATER ASSY RH 
    1. Inspect the seat cushion thermostat continuity.
      1. Disconnect the seat back heater from the seat cushion heater.
      2. Heat the temperature sensor and thermostat with a light.
      3. Inspect the seat cushion heater continuity between terminals, as shown.
        Fig 1: Identifying Front Seat Cushion Heater Assy RH Connector Terminal
        G03484207Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

        Standard: 

        FRONT SEAT CUSHION HEATER ASSY RH TERMINAL SPECIFICATION

        Terminal No. Condition Specified condition
        S20-1 <=> 2 Seat heater temp. below 25 - 35 °C (77 - 95 °F) 8,000 - 8,400 Ω
        S20-1 <=> 2 Seat heater temp. 46 - 54 °C (115 - 129 °F) 3,900 - 4,300 Ω
        S20-3 <=> 1 Seat heater temp. below 25 - 35 °C (77 - 95 °F) Continuity
        S20-3 <=> 1 Seat heater temp. 46 - 54 °C (115 - 129 °F) No continuity (thermostat OFF)
        S20-3 <=> 2 Seat heater temp. below 25 - 35 °C (77 - 95 °F) Continuity
        S20-3 <=> 2 Seat heater temp. 46 - 54 °C (115 - 129 °F) No continuity (thermostat OFF)
        S20-4 <=> 1 Constant Continuity

        If continuity is not as specified, replace the seat cushion heater assembly.

  2. INSPECT FRONT SEAT CUSHION HEATER ASSY LH 
    1. Inspect the seat cushion thermostat continuity.
      1. Disconnect the seat back heater from the seat cushion heater.
      2. Heat the temperature sensor and thermostat with a light.
      3. Inspect the seat cushion heater continuity between terminals, as shown.
        Fig 2: Identifying Front Seat Cushion Heater Assy LH Connector Terminal
        G03484208Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

        Standard: 

        FRONT SEAT CUSHION HEATER ASSY LH TERMINAL SPECIFIED CONDITION CHART

        Terminal No. Condition Specified condition
        S22-1 <=> 2 Seat heater temp. below 25 - 35 °C (77 - 95 °F) 8,000 - 8,400 Ω
        S22-1 <=> 2 Seat heater temp. 46 - 54 °C (115 - 129 °F) 3,900 - 4,300 Ω
        S22-3 <=> 1 Seat heater temp. below 25 - 35 °C (77 - 95 °F) Continuity
        S22-3 <=> 1 Seat heater temp. 46 - 54 °C (115 - 129 °F) No continuity (thermostat OFF)
        S22-3 <=> 2 Seat heater temp. below 25 - 35 °C (77 - 95 °F) Continuity
        S22-3 <=> 2 Seat heater temp. 46 - 54 °C (115 - 129 °F) No continuity (thermostat OFF)
        S22-4 <=> 1 Constant Continuity

        If continuity is not as specified, replace the seat cushion heater assembly.

  3. INSPECT FRONT SEAT BACK HEATER ASSY RH 
    1. Inspect the seatback heater assembly RH continuity.

      Standard: 

      FRONT SEAT BACK HEATER ASSY RH TERMINAL SPECIFIED CONDITION CHART

      Terminal No. Condition Specified condition
      1 - 2 Constant Continuity

      If continuity is not as specified, replace the seatback heater assembly.

      Fig 3: Identifying Front Seat Back Heater Assy RH Connector Terminal
      G03484209Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  4. INSPECT FRONT SEAT BACK HEATER ASSY LH 
    1. Inspect the seatback heater assembly LH continuity.

      Standard: 

      FRONT SEAT BACK HEATER ASSY LH TERMINAL SPECIFIED CONDITION CHART

      Terminal No. Condition Specified condition
      1 - 2 Constant Continuity

      If continuity is not as specified, replace the seatback heater assembly.

      Fig 4: Identifying Front Seat Back Heater Assy LH Connector Terminal
      G03484210Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.