Combustion Type Power Heater System - Power Heater Switch Circuit

Lexus IS250 IS220d GSE20 ALE20 - HEATER

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

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

INSPECTION PROCEDURE

1.INSPECT POWER HEATER SWITCH
Combustion Type Power Heater System - Power Heater Switch Circuit. HEATER. Lexus IS250 IS220d GSE20 ALE20

Measure the resistance.


Remove the power heater switch.

Disconnect the connector from the power heater switch.

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

  • Standard resistance:
  • Tester connection
    (Symbols)    		ConditionSpecified condition
    J95-3 (IG) - J95-4 (IN)Power heater switch: ONBelow 1 Ω
    J95-3 (IG) - J95-4 (IN)Power heater switch: OFF10 kΩ or higher

Check that the power heater switch operation indicator comes on.


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.

Check that the power heater switch illumination comes on.


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)

Remove the power heater ECU (combustion heater assembly).

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

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

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

  • Standard voltage:
  • Tester connection
    (Symbols)    		ConditionSpecified condition
    A51-3 (IG) - Body groundEngine switch: on (IG)
    Power heater switch: ON    		10 to 14 V
    A51-3 (IG) - Body groundEngine 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)
Combustion Type Power Heater System - Power Heater Switch Circuit. HEATER. Lexus IS250 IS220d GSE20 ALE20

Disconnect the connector from the power heater switch.

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

  • Standard resistance:
  • Tester connection
    (Symbols)    		ConditionSpecified condition
    J95-6 (E) - Body groundAlwaysBelow 1 Ω
NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK
PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE