COMBUSTION TYPE POWER HEATER SYSTEM Power Heater Fuel Pump Circuit

DESCRIPTION

When the heater switch assembly is turned on, the heater fuel pump sub-assembly receives a drive voltage from the power heater ECU (combustion heater assembly). The heater fuel pump sub-assembly provides the combustion heater with fuel necessary for combustion, allowing the combustion heater to operate.

WIRING DIAGRAM

A005L8DE03
*a HEATER FUEL PUMP SUB-ASSEMBLY
*b POWER HEATER ECU (COMBUSTION HEATER ASSEMBLY)

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (COMBUSTION HEATER ASSEMBLY - HEATER FUEL PUMP SUB-ASSEMBLY)


    1. Disconnect the A29 power heater ECU (combustion heater assembly) connector.

    2. Disconnect the A30 heater fuel pump sub-assembly connector.

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

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      A29-2 (L) - A30-1 (+B) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      A29-2 (L) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. CHECK HARNESS AND CONNECTOR (HEATER FUEL PUMP SUB-ASSEMBLY - BODY GROUND)


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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A30-2 (E2) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. INSPECT HEATER FUEL PUMP SUB-ASSEMBLY


    1. A005IGRE09
      Text in Illustration
      *a

      Component without harness connected

      (Heater pump assembly)

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A30-1 (+B) - A30-2 (E2) Always 9 to 12 Ω

    2. Inspect heater fuel pump sub-assembly operation.


      1. Connect the positive (+) lead from the battery to terminal 1 and the negative (-) lead to terminal 2, and check the pressure of the hose by hand.

        CAUTION:


        • This inspection must be done quickly (within 10 seconds) to prevent damage to the heater fuel pump sub-assembly.

        • Always switch the voltage on and off on the battery side, not the heater fuel pump sub-assembly side.

        • Keep the heater fuel pump sub-assembly as far away from the battery as possible.

        OK
        Pressure is applied to the hose.

    OK

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

    NG

    REPLACE HEATER FUEL PUMP SUB-ASSEMBLY Click here