Combustion Type Power Heater System - Power Heater Alternator Circuit

Lexus IS250 IS220d GSE20 ALE20 - HEATER

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

Combustion Type Power Heater System - Power Heater Alternator Circuit. HEATER. Lexus IS250 IS220d GSE20 ALE20

INSPECTION PROCEDURE

1.INSPECT ALTERNATOR

Inspect the alternator (for ON-VEHICLE INSPECTION, for INSPECTION).

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

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

Combustion Type Power Heater System - Power Heater Alternator Circuit. HEATER. Lexus IS250 IS220d GSE20 ALE20

Disconnect the connector from the alternator.

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

  • Standard resistance:
  • Tester connection
    (Symbols)    		ConditionSpecified condition
    A51-8 (+) - E82-4 (L)AlwaysBelow 1 Ω
    A51-8 (+) - Body groundAlways10 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)

Reconnect the connector to the alternator.

Combustion Type Power Heater System - Power Heater Alternator Circuit. HEATER. Lexus IS250 IS220d GSE20 ALE20

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

  • Standard voltage:
  • Tester connection
    (Symbols)    		ConditionSpecified condition
    A51-8 (+) - Body groundEngine 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