Combustion Type Power Heater System Power Heater Switch Circuit

Heater & Air Conditioning System. Lexus Is250, Is220D. Gse20 Ale20
Heater. Lexus Is250, Is220D. Gse20 Ale20

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

INSPECT POWER HEATER SWITCH

CHECK HARNESS AND CONNECTOR (POWER HEATER ECU (COMBUSTION HEATER ASSEMBLY) - BATTERY)

CHECK HARNESS AND CONNECTOR (POWER HEATER SWITCH - BODY GROUND)

COMBUSTION TYPE POWER HEATER SYSTEM - Power Heater Switch Circuit


DESCRIPTION

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

WIRING DIAGRAM


Lexus Is250, Is220D. Gse20 Ale20.Heater.Combustion Type Power Heater System.Combustion Type Power Heater System Power Heater Switch Circuit


INSPECTION PROCEDURE

1.INSPECT POWER HEATER SWITCH


    Lexus Is250, Is220D. Gse20 Ale20.Heater.Combustion Type Power Heater System.Combustion Type Power Heater System Power Heater Switch Circuit

  1. Measure the resistance.

    1. Remove the power heater switch.

    2. Disconnect the connector from the power heater switch.

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

      Standard resistance:
      Tester connection
      (Symbols)
      		Condition
      		Specified condition
      J95-3 (IG) - J95-4 (IN)
      		Power heater switch: ON
      		Below 1 Ω
      J95-3 (IG) - J95-4 (IN)
      		Power heater switch: OFF
      		10 kΩ or higher

  1. Check that the power heater switch operation indicator comes on.

    1. Connect the positive (+) lead from the battery to terminal 4 (IN) and the negative (-) lead to terminal 6 (E), and check that the operation indicator comes on.

      OK:
      Indicator comes on.

  1. Check that the power heater switch illumination comes on.

    1. Connect the positive (+) lead from the battery to terminal 1 (ILL+) and the negative (-) lead to terminal 2 (ILL-), and check that the switch illumination comes on.

      OK:
      Illumination comes on.


NG
REPLACE POWER HEATER SWITCH
OK


2.CHECK HARNESS AND CONNECTOR (POWER HEATER ECU (COMBUSTION HEATER ASSEMBLY) - BATTERY)

  1. Remove the power heater ECU (combustion heater assembly).



    Lexus Is250, Is220D. Gse20 Ale20.Heater.Combustion Type Power Heater System.Combustion Type Power Heater System Power Heater Switch Circuit

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

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

    Standard voltage:
    Tester connection
    (Symbols)
    		Condition
    		Specified condition
    A51-3 (IG) - Body ground
    		Engine switch: on (IG)
    Power heater switch: ON
    		10 to 14 V
    A51-3 (IG) - Body ground
    		Engine switch: on (IG)
    Power heater switch: OFF
    		Below 1 V


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


3.CHECK HARNESS AND CONNECTOR (POWER HEATER SWITCH - BODY GROUND)


    Lexus Is250, Is220D. Gse20 Ale20.Heater.Combustion Type Power Heater System.Combustion Type Power Heater System Power Heater Switch Circuit

  1. Disconnect the connector from the power heater switch.

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

    Standard resistance:
    Tester connection
    (Symbols)
    		Condition
    		Specified condition
    J95-6 (E) - Body ground
    		Always
    		Below 1 Ω


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE