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Home >> Lexus >> 2024 >> TX 350 Base, FWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 117 (Heating / Air Conditioning System - Diagnostic Codes (3 Of 3) & Symptom Tests) >> AIR CONDITIONING SYSTEM (for PHEV Model) >> No Heating at All [12/2023 - ] >> Procedure

No Heating at All [12/2023 - ]: Procedure

WARNING: This page is about a different car, the 2024 Lexus TX 550h+. However, it is still accessible from the selected car via links, so may be relevant.
  1. READ VALUE USING GTS (COOLANT TEMPERATURE) 
    1. Read the Data List according to the display on the GTS.

      Powertrain > Engine > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Coolant Temperature Engine coolant temperature Min.: -40°C (-40°F)
      Max.: 140°C (284°F)      		 75 to 100°C (167 to 212°F): After warming up This is the engine coolant temperature.
      HINT: 
      • After warming up the engine, the engine coolant temperature will be 75 to 100°C (167 to 212°F).
      • After a long soak, the engine coolant temperature, intake air temperature and ambient air temperature will be approximately equal.
      • If the value is -40°C (-40°F), or higher than 135°C (275°F), the sensor circuit is open or shorted.
      • Check if the engine overheats if the value indicated is higher than 135°C (275°F).

      Powertrain > Engine > Data List 

      Tester Display
      Coolant Temperature

      OK

      The value of the display does not change frequently.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    GO TO COOLING SYSTEM. Refer to  ON-VEHICLE INSPECTION [12/2023 - ] 

    Result: 

    OK 

    See step  2

  2. PERFORM ACTIVE TEST USING GTS 
    1. Perform the Active Test according to the display on the GTS.

      Body Electrical > Air Conditioner > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      Front Left Air Mix Damper Control Servo Motor This test activates the Front Left Air Mix Damper Control Servo Motor.
      (No. 1 air conditioning radiator damper servo sub-assembly (front left side air mix))      		 128: Min
      384: Max      		 Operate with ignition switch ON.
      Front Right Air Mix Damper Control Servo Motor This test activates the Front Right Air Mix Damper Control Servo Motor.
      (No. 1 air conditioning radiator damper servo sub-assembly (front right side air mix))      		 128: Min
      384: Max      		 Operate with ignition switch ON.
      Rear Air Mix Damper Control Servo Motor This test activates the rear air mix damper control servo motor.
      (Rear air mix damper servo sub-assembly)      		 128: Min
      384: Max      		 Operate with ignition switch ON.

      Body Electrical > Air Conditioner > Active Test 

      Active Test Display
      Front Left Air Mix Damper Control Servo Motor
      Data List Display
      Front Left Air Mix Damper Control Servo Motor Actual Pulse

      Body Electrical > Air Conditioner > Active Test 

      Active Test Display
      Front Right Air Mix Damper Control Servo Motor
      Data List Display
      Front Right Air Mix Damper Control Servo Motor Actual Pulse

      Body Electrical > Air Conditioner > Active Test 

      Active Test Display
      Rear Air Mix Damper Control Servo Motor
      Data List Display
      Rear Air Mix Damper Control Servo Motor Actual Pulse

      OK

      Damper servo motor is operated.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    GO TO DIAGNOSTIC TROUBLE CODE CHART (FOR SERVO MOTOR OF APPLICABLE ABNORMAL OPERATION). Refer to  DIAGNOSTIC TROUBLE CODE CHART [12/2023 - ] 

    Result: 

    OK 

    See step  3

  3. CHECK HIGH VOLTAGE ELECTRIC HEATER (ELECTRIC HEATER SUB-ASSEMBLY) 
    1. Perform the Active Test according to the display on the GTS.

      Body Electrical > Air Conditioner > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      High Voltage Electric Heater This test activates High Voltage Electric Heater.
      (High voltage electric heater (electric heater sub-assembly))      		 OFF: Stopped
      ON: Operating
      • Ignition switch ON (READY)
      • Vehicle stopped
      • EV Mode
      • A/C Switch: ON
      • Mode: Except for DEF
      • Blower: HI
      • Set Temperature: MAX HOT

      Body Electrical > Air Conditioner > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      High Voltage Electric Heater Consumption Electric Power High voltage electric heater (electric heater sub-assembly) consumption electric power 0 to 7000 W Actual high voltage electric heater (electric heater sub-assembly) consumption electric power displayed -

      Body Electrical > Air Conditioner > Active Test 

      Active Test Display
      High Voltage Electric Heater
      Data List Display
      High Voltage Electric Heater Consumption Electric Power

      OK

      The value of the Data List item changes in accordance with the operation of the Active Test.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE HIGH VOLTAGE ELECTRIC HEATER (ELECTRIC HEATER SUB-ASSEMBLY). Refer to  REMOVAL [12/2023 - ] 

    Result: 

    OK 

    See step  4

  4. CHECK HEATING THREE-WAY VALVE (HEATER WATER VALVE ASSEMBLY) 
    1. Check the operation by referring to the table below.

      Body Electrical > Air Conditioner > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      Heater Valve This test changes the heater valve to Open/Half/Close.
      (Heating three-way valve (heater water valve assembly))      		 Close: Valve Close Position
      Half: Valve Middle Position
      Open: Valve Open Position      		 Operate with the ignition switch ON (READY).

      Body Electrical > Air Conditioner > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Heating Three-way Valve Target Position Target opening angle of heating three-way valve (heater water valve assembly) 0 to 100 % Target opening angle Heating three-way valve (heater water valve assembly) circuit malfunction
      • Combination: 0%
      • Single: 100%
      Heating Three-way Valve Actual Position Actual opening angle of heating three-way valve (heater water valve assembly) 0 to 100 % Actual opening angle following the target opening angle Heating three-way valve (heater water valve assembly) circuit malfunction
      • Combination: 0%
      • Single: 100%
      Heater Valve Operation condition of heating three-way valve (heater water valve assembly) Close / Half / Open
      • Close: Target angle 100% (Single)
      • Half: Target angle 50%
      • Open: Target angle 0% (Combination)
      		 Heating three-way valve (heater water valve assembly) circuit malfunction

      Body Electrical > Air Conditioner > Active Test 

      Active Test Display
      Heater Valve
      Data List Display
      Heating Three-way Valve Target Position
      Heating Three-way Valve Actual Position
      Heater Valve

      OK

      Heating three-way valve (heater water valve assembly) is operated.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE HEATING THREE-WAY VALVE (HEATER WATER VALVE ASSEMBLY). Refer to  REMOVAL [12/2023 - ] 

    Result: 

    OK 

    See step  5

  5. CHECK ELECTRIC WATER PUMP (REAR HEATER PUMP ASSEMBLY) 
    1. Check the operation by referring to the table below.

      Body Electrical > Air Conditioner > Active Test 

      Tester Display Measurement Item Control Range Diagnostic Note
      Water Pump This test activates the water pump. Water pump operation can be verified by sound from inside the vehicle.
      (Electric water pump (rear heater pump assembly))      		 ON: Drive
      OFF: Stop      		 Operate with the ignition switch ON (READY).

      Body Electrical > Air Conditioner > Data List 

      Tester Display Measurement Item Range Normal Condition Diagnostic Note
      Water Pump Operation condition of the electric water pump (rear heater pump assembly) OFF / ON ON: Electric water pump (rear heater pump assembly) operating
      OFF: Electric water pump (rear heater pump assembly) not operating      		 -

      Body Electrical > Air Conditioner > Active Test 

      Active Test Display
      Water Pump
      Data List Display
      Water Pump

      OK

      Electric water pump (rear heater pump assembly) is operated.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPLACE HEATER RADIATOR UNIT SUB-ASSEMBLY. Refer to  DISASSEMBLY [12/2023 - ] 

    Result: 

    NG 

    REPLACE ELECTRIC WATER PUMP (REAR HEATER PUMP ASSEMBLY). Refer to  REMOVAL [12/2023 - ] 

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