Window Defogger System (Diagnostics): Overview Lexus GS III рестайлинг

SYSTEM DESCRIPTION

1. GENERAL The defogger system's thin heater wires are attached to the inside of the rear window and defog the window surface quickly. The indicator light illuminates while the system is operating. The system automatically turns off after approximately 15 minutes. HINT: The rear window defogger is linked with the mirror defogger.
2. FUNCTION OF MAIN COMPONENT Component Outline DEFOG Relay Receives rear defogger activation request signals from air conditioning amplifier (A/C ECU) and supplies power to rear window defogger Rear Window Defogger Receives power from DEFOG relay and heats defogger wires
3. DESCRIPTION Function Outline Rear window surface defogger Receives rear defogger activation request signals from air conditioning amplifier (A/C ECU) and supplies power to rear window defogger Receives power from DEFOG relay and heats defogger wires

DESCRIPTION

When the defogger switch is turned ON, a rear defogger activation request signal is input to the multi-display. Then, the air conditioning amplifier (A/C ECU) outputs this signal to the defogger relay (Marking: DEFOG) and the rear window defogger system is activated.

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1. CHECK OPERATION Check that the engine starts normally. OK Engine starts normally. NG --> See step 10 OK: Go to next step
2. PERFORM ACTIVE TEST USING TECHSTREAM (REAR WINDOW DEFOGGER) Using the Techstream ACTIVE TEST, generate a control command and then check that the rear window defogger operates. AIR CONDITIONING AMPLIFIER (A/C ECU) Tester Display Test Part Control Range Defogger Relay (Rear) Operate rear window defogger OFF / ON RESULT Result Proceed to Rear window defogger operates normally A Rear window defogger operates abnormally B B --> See step 4 A: Go to next step
3. CHECK OPERATION OF MULTI-DISPLAY WITH NEW OR NORMALLY FUNCTIONING MULTI-DISPLAY Temporarily replace the multi-display with a new or normally functioning one. Check that the malfunction disappears. OK Malfunction disappears. NG --> REPLACE AIR CONDITIONING AMPLIFIER OK --> REPLACE MULTI-DISPLAY
4. INSPECT FUSE (DEFOG, AM2, LH-IG) Remove the DEFOG fuse from the engine room No. 1 relay block. Remove the AM2 fuse from the main body ECU RH. Remove the LH-IG fuse from the main body ECU LH. Measure the resistance of the fuses. Standard resistance Below 1 ohms NG --> REPLACE FUSE OK: Go to next step
5. INSPECT DEFOGGER RELAY (Marking: DEFOG) Remove the defogger relay from the engine room No. 1 relay block. Measure the resistance of the relay. Standard resistance Tester Connection Specified Condition 3 - 4 Below 1 ohms 3 - 5 10 kohms or higher 3 - 4 10 kohms or higher (when battery voltage is applied to terminals 1 and 2) 3 - 5 Below 1 ohms (when battery voltage is applied to terminals 1 and 2) NG --> REPLACE DEFOGGER RELAY OK: Go to next step
6. CHECK WIRE HARNESS (DEFOGGER RELAY - ECM AND BATTERY) Remove the defogger relay from the engine room No. 1 relay block. Disconnect the A53 ECM connector. Measure the voltage of the wire harness side connectors. Standard voltage Tester Connection Condition Specified Condition Relay block defogger relay terminal 1 - Body ground Power switch ON (IG) 10 to 14 V Relay block defogger relay terminal 5 - Body ground Always 10 to 14 V Measure the resistance of the wire harness side connectors. Standard resistance Tester Connection Specified Condition Relay block defogger relay terminal 2 - A53-14 (RDEF) Below 1 ohms NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
7. CHECK WIRE HARNESS (REAR WINDOW DEFOGGER - DEFOGGER RELAY AND BODY GROUND) Disconnect the U20 and V20 defogger connectors. Disconnect the defogger relay from the engine room No. 1 relay block. Measure the resistance of the wire harness side connectors. Standard resistance Tester Connection Specified Condition V20-1 - Relay block DEFOG relay terminal 3 Below 1 ohms U20-1 - Body ground Below 1 ohms Relay block DEFOG relay terminal 4 - Body ground Below 1 ohms V20-1 - Body ground 10 kohms or higher NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
8. INSPECT REAR WINDOW DEFOGGER WIRE Turn the power switch ON (IG). Turn the defogger switch ON. Check the voltage at the center of each defogger wire, as shown in the illustration. Standard voltage Voltage Criteria Approx. 5 V Wire is not broken Approx. 10 or 0 V Wire is broken HINT: If there is approximately 10 V, the wire may be faulty between the center of the wire and the wire end on the battery side. If there is no voltage, the wire may be faulty between the center of the wire and the wire end on the ground side. NOTE: When measuring voltage, wrap a piece of tin foil around the tip of the negative tester probe and press the foil against the wire with your finger, as shown in the illustration. Place the voltmeter's positive (+) lead against the defogger wire on the battery side. Place the voltmeter's negative (-) lead with the foil strip against the wire on the ground side. Slide the positive (+) lead from the battery side to the ground side. The point where the voltage drops from approximately 10 V to 0 V is where the defogger wire is broken. HINT: If the defogger wire is not broken, the voltmeter should indicate 0 V at the positive (+) end of the defogger wire and gradually increase to approximately 12 V as the meter probe is moved to the other end. NG --> REPAIR REAR WINDOW DEFOGGER WIRE OK: Go to next step
9. CHECK OPERATION OF ECM WITH NEW OR NORMALLY FUNCTIONING ECM Temporarily replace the ECM with a new or normally functioning one. Check that the malfunction disappears. OK Malfunction disappears. NG --> REPLACE AIR CONDITIONING AMPLIFIER (A/C ECU) OK --> REPLACE ECM
10. GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START. Refer to «HOW TO PROCEED WITH TROUBLESHOOTING»(ref-387105-S14071125202011022400000)