Lexus IS250 · Service Manual BODY

Windshield Deicer does not Operate

Circuit diagnosis

DESCRIPTION

Pressing the windshield deicer switch with the engine switch on (IG) causes the indicator to come on and the system to be activated. After approximately 15 minutes, the system automatically stops and the indicator goes off.

WIRING DIAGRAM

B127530E02

INSPECTION PROCEDURE


1. CHECK WIRE HARNESS (WINDSHIELD DEICER SWITCH)

  1. B127519E01
    Disconnect the windshield deicer switch.

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

    Voltage:
    Tester Connection
    		 Condition
    		 Specified Condition
    J90-5 (IG) - Body ground
    		 Engine switch on (IG)
    		 10 to 14 V

    Resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    J90-3 - Body ground
    		 Always
    		 Below 1 Ω



NG
REPAIR OR REPLACE WIRE HARNESS
OK


2. INSPECT WINDSHIELD DEICER SWITCH

  1. E105443E01
    Measure the voltage according to the value(s) in the table below (connector still connected).

    Resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    J90-4 (D) - J90-3 (E)
    		 Engine switch on (IG), windshield deicer switch OFF → ON
    		 Below 1 V → 10 to 14 V
    J90-5 (IG) - J90-3 (E)
    		 Windshield deicer switch ON → OFF
    		 10 to 14 V → Below 1 V



NG
REPLACE WINDSHIELD DEICER SWITCH
OK


3. SYSTEM CHECK

  1. Check that the indicator comes on after the engine switch has been turned on (IG) and the windshield deicer switch has been pressed.

    Result:
    Indicator off
    		 A
    Indicator on
    		 B



B
Go to step 6
A


4. CHECK WIRE HARNESS (DEICER RELAY - BATTERY POSITIVE AND BODY GROUND)

  1. B127520E01
    Disconnect the DEICER relay.

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

    Voltage:
    Engine Room R/B No. 3:
    Tester Connection
    		 Condition
    		 Specified Condition
    1 - Body ground
    		 Engine switch on (IG)
    		 10 to 14 V



NG
REPAIR OR REPLACE RH-IG FUSE OR HARNESS AND CONNECTOR
OK


5. CHECK WIRE HARNESS (DEICER RELAY - WINDSHIELD DEICER SWITCH)

  1. B127522E01
    Disconnect the DEICER relay and windshield deicer switch.

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

    Resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    2 - J90-4 (D)
    		 Always
    		 Below 1 Ω
    2 - Body ground
    		 Always
    		 10 kΩ or higher



NG
REPAIR OR REPLACE WIRE HARNESS
OK

REPLACE WINDSHIELD DEICER RELAY

6. CHECK WIRE HARNESS (DEICER RELAY - BATTERY POSITIVE AND BODY GROUND)

  1. B127520E01
    Disconnect the DEICER relay.

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

    Voltage:
    Engine Room R/B No. 3:
    Tester Connection
    		 Condition
    		 Specified Condition
    3 - Body ground
    		 Engine switch on (IG)
    		 10 to 14 V



NG
REPAIR OR REPLACE DEICER FUSE OR HARNESS AND CONNECTOR
OK


7. CHECK WIRE HARNESS (DEICER RELAY - WINDSHIELD DEICER WIRE)

  1. B127524E01
    Disconnect the DEICER relay and windshield deicer switch.

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

    Resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    5 - A44-1 (B2)
    		 Always
    		 Below 1 Ω
    5 - A44-2 (B)
    		 Always
    		 Below 1 Ω
    5 - Body ground
    		 Always
    		 10 kΩ or higher



NG
REPAIR OR REPLACE WIRE HARNESS
OK


8. INSPECT WINDSHIELD DEICER RELAY
Click here


NG
REPLACE WINDSHIELD DEICER RELAY
OK


9. CHECK WIRE HARNESS (WINDSHIELD DEICER WIRE - BODY GROUND)

  1. B069720E02
    Disconnect the windshield deicer wire.

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

    Resistance:
    Tester Connection
    		 Condition
    		 Specified Condition
    A44-3 (E) - Body ground
    		 Always
    		 Below 1 Ω



NG
REPAIR OR REPLACE WIRE HARNESS
OK

REPLACE WINDSHIELD DEICER WIRE


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