COMBUSTION TYPE POWER HEATER SYSTEM Power Heater Switch Circuit

DESCRIPTION

When the power heater switch (air conditioning control assembly) is turned on, the ECU (heater assembly) sends a drive signal to the heater pump assembly. The heater assembly then receives the fuel necessary for combustion and starts operating.

WIRING DIAGRAM

A004TCWE02
*a Air Conditioning Control Assembly
*b Heater Assembly
*c from Engine Stop and Start ECU

CAUTION / NOTICE / HINT

Tech Tips

Before performing the following procedures, check the battery and confirm that they are operating normally.

PROCEDURE


  1. INSPECT AIR CONDITIONING CONTROL ASSEMBLY


    1. A004QBVE01
      Text in Illustration
      *1

      Component without harness connected

      (Air Conditioning Control Assembly)

      Remove the air conditioning control assembly Click here.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Switch Condition Specified Condition
      5 (IG+) - 4 (IN) Power heater switch on Below 1 Ω
      5 (IG+) - 4 (IN) Power heater switch off 10 kΩ or higher

    3. Connect the positive (+) lead from the battery to terminal 5 (IG+) and the negative (-) lead to terminal 11 (GND), and check that the operation indicator comes on.

      OK
      The power heater switch operation indicator comes on.

    NG

    REPLACE AIR CONDITIONING CONTROL ASSEMBLY Click here

    OK

  2. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING CONTROL - BATTERY AND BODY GROUND)

    A004QUCE01
    Text in Illustration
    *1

    Front view of wire harness connector

    (to Air Conditioning Control Assembly)

    1. Disconnect the D12 air conditioning control assembly connector.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      D12-11 (GND) - Body ground Always Below 1 Ω

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      D12-5 (IG+) - Body ground Ignition switch ON 10.5 to 16 V
      D12-5 (IG+) - Body ground Ignition switch off Below 1 V

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK HARNESS AND CONNECTOR (HEATER ASSEMBLY - BATTERY)


    1. A004Q56E02
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Heater Assembly)

      Disconnect the A54 heater assembly connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A54-3 (IG) - Body ground

      Ignition switch ON

      Power heater switch on

      		 10.5 to 16 V
      A54-3 (IG) - Body ground

      Ignition switch ON

      Power heater switch off

      		 Below 1 V

    OK

    PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR