Combustion Type Power Heater System Power Heater Alternator Circuit

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

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

INSPECT ALTERNATOR

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

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

COMBUSTION TYPE POWER HEATER SYSTEM - Power Heater Alternator Circuit


DESCRIPTION

When the alternator does not generate electricity, current flows from the IG2 relay to power heater resistors No. 1 and No. 2. Then the current flows to the diode (for power heater), terminal E82-4 (L) of the alternator, and then to ground. As a result, the power heater ECU will not activate.
When the alternator generates electricity, the current flows from the IG2 relay to power heater resistors No. 1 and No. 2, and then to terminal A51-8 (+), and the power heater ECU determines that the engine is running.

WIRING DIAGRAM


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


INSPECTION PROCEDURE

1.INSPECT ALTERNATOR

  1. Inspect the alternator (Click herefor ON-VEHICLE INSPECTION, Click here for INSPECTION).



NG
REPLACE ALTERNATOR
OK


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

  1. Disconnect the connector from 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 Alternator Circuit

  1. Disconnect the connector from the alternator.

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

    Standard resistance:
    Tester connection
    (Symbols)
    		Condition
    		Specified condition
    A51-8 (+) - E82-4 (L)
    		Always
    		Below 1 Ω
    A51-8 (+) - Body ground
    		Always
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER HEATER ECU (COMBUSTION HEATER ASSEMBLY) - ALTERNATOR)
OK


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

  1. Reconnect the connector to the alternator.



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

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

    Standard voltage:
    Tester connection
    (Symbols)
    		Condition
    		Specified condition
    A51-8 (+) - Body ground
    		Engine is running.
    (Alternator: Operate)
    		10 to 14 V


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR (POWER HEATER ECU (COMBUSTION HEATER ASSEMBLY) - BATTERY)
OK

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE