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Home >> Lexus >> 2008 >> IS 350 >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Air Conditioning >> Air Conditioning System >> PTC Heater Circuit >> Inspection Procedure

Inspection Procedure

  1. INSPECT FUSE (LH-IG, GLW PLG1, GLW PLG2) 
    1. Remove the LH-IG fuse from the cowl side J/B LH.
      Fig 1: Identifying LH-IG Fuse
      G05831458Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Remove the GLW PLG1 and GLW PLG2 fuses from the engine room R/B and J/B No. 1.
    3. Measure the resistance according to the value (s) in the table below.

      Standard resistance 

      STANDARD RESISTANCE SPECIFICATIONS

      Tester Item Condition Specified Condition
      LH-IG fuse Always Below 1 Ω
      GLW PLG1 fuse Always Below 1 Ω
      GLW PLG2 fuse Always Below 1 Ω
      4. Fig 2: Identifying GLW PLG1 And GLW PLG2
      G05831459Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE FUSE 

    OK: Go to Next Step 

  2. INSPECT RELAY (GLW RLY1, GLW RLY2) 
    1. Remove the GLW RLY1 and GLW RLY2 relays from the engine room R/B and J/B No. 1.
    2. Measure the resistance according to the value (s) in the table below.

      Standard resistance 

      TESTER CONNECTION AND SPECIFIED CONDITION

      Tester Connection Condition Specified Condition
      3-5 Always 10 kΩ or higher
      3-5 When battery voltage is applied to terminals 1 and 2 Below 1 Ω
      3. Fig 3: Identifying Relay (A/C W/P)
      G05012136Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE RELAY 

    OK: Go to Next Step 

  3. CHECK HARNESS AND CONNECTOR (A/C AMPLIFIER - BATTERY) 
    1. Disconnect the connector from the A/C amplifier.
    2. Turn the engine switch on (IG).
    3. Measure the voltage according to the value (s) in the table below.

      Standard voltage 

      TESTER CONNECTION AND SPECIFIED CONDITION

      Tester Connection (Symbols) Condition Specified Condition
      J58-4 (HTR2) - Body ground Engine switch on (IG) 10 to 14 V
      J58-23 (HTR1) - Body ground Engine switch on (IG) 10 to 14 V
      4. Fig 4: Identifying Connector From A/C Amplifier
      G05831461Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to Next Step 

  4. INSPECT AIR CONDITIONING AMPLIFIER 
    1. Reconnect the connector to the A/C amplifier.
    2. Measure the voltage according to the value (s) in the table below.
      Fig 5: Identifying Connector To A/C Amplifier
      G05831462Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Standard voltage 

      TESTER CONNECTION AND SPECIFIED CONDITION

      Tester Connection Condition Specified Condition
      J58-4 (HTR2) - Body ground Engine switch on (IG) 10 to 14 V
      J58-4 (HTR2) - Body ground Engine switch on (IG) While the PTC operating conditions are met (engine is running at 850 rpm or more, ambient temperature is 0°C (32°F) or less, engine coolant temperature is 69°C (156°F) or less, and A/C switch setting is MAX HOT), turn the blower switch to the LO setting. Below 1 V
      J58-23 (HTR1) - Body ground Engine switch on (IG) 10 to 14 V
      D47-2 - Body ground Engine switch on (IG) While the PTC operating conditions are met (engine is running at 850 rpm or more, ambient temperature is 0°C (32°F) or less, engine coolant temperature is 69°C (156°F) or less, and A/C switch setting is MAX HOT), turn the blower switch to the LO setting. Below 1 V

    NG: REPLACE AIR CONDITIONING AMPLIFIER 

    OK: Go to Next Step 

  5. INSPECT HEATER BLOWER WIRE 
    1. Remove the grommets and nuts of the water by-pass glow plugs.
    2. Turn the engine switch on (IG).
    3. Perform Active Test by referring to the table below.

      Active Test / Air Conditioner: 

      TESTER DISPLAY FUNCTIONS

      Tester Display Test Part Control Range Diagnostic Note
      Electric Heater1 (Heater1) Electric Heater 1 OFF, ON -
      Electric Heater2 (Heater2) Electric Heater 2 OFF, ON -
    4. Measure the voltage according to the value (s) in the table below.

      Standard voltage 

      TESTER CONNECTION AND SPECIFIED CONDITION

      Tester connection Condition Specified condition
      1 - Body ground Perform ACTIVE TEST/ HEATER 1 (Electric Heater 1): ON 10 to 14 V
      2 - Body ground Perform ACTIVE TEST/ HEATER 2 (Electric Heater 2): ON 10 to 14 V
      5. Fig 6: Identifying Heater Blower Wire Terminals
      G05831463Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HEATER BLOWER WIRE 

    OK: Go to Next Step 

  6. INSPECT WATER BY-PASS GLOW PLUG 
    1. Remove the water by-pass glow plug.
    2. Measure the resistance according to the value (s) in the table below.

      Standard resistance: 

      Below 1 Ω 

      3. Fig 7: Inspecting Water By-Pass Glow Plug
      G05297799Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPLACE WATER BY-PASS GLOW PLUG 

    OK: PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN  PROBLEM SYMPTOMS TABLE  

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