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Winddow Defogger (Diagnostics): Overview Lexus GS III facelift

Windows 8 illustrations ~1078 words

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 A/C amplifier assembly (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 Defogs the rear window surface Receives rear defogger activation request signals from A/C amplifier assembly (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 A/C amplifier assembly (A/C ECU) outputs this signal to the defogger relay (Marking: DEFOG) and the rear window defogger system is activated.

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Scheme 122: WIRING DIAGRAM

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Scheme 124: PROCEDURE
Scheme 124: PROCEDURE

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  1. CHECK OPERATION Check that the engine starts normally. OK Engine starts normally. NG --> GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START 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. A/C Amplifier Assembly (A/C ECU) Tester Display Test Part Control Range Diagnostic Note 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 ASSEMBLY OK --> REPLACE MULTI-DISPLAY
  4. INSPECT FUSE (DEFOG, ALT, LH J/B-AM, RH J/B-B, AM2, LH-IG) Remove the DEFOG, ALT, LH J/B-AM and RH J/B-B fuses from the engine room No. 1 relay block. Remove the AM2 fuse from the cowl side junction block RH. Remove the LH-IG fuse from the cowl side junction block LH. Measure the resistance of the fuses. Standard resistance Below 1 ohms NG --> REPLACE FUSE OK: Go to next step
  5. INSPECT RELAY (DEFOG) Remove the DEFOG 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 - 5 Below 1 ohms (when battery voltage is applied to terminals 1 and 2) NG --> REPLACE RELAY OK: Go to next step
  6. CHECK WIRE HARNESS (ENGINE ROOM NO. 1 RELAY BLOCK - ECM AND BATTERY) for 3GR-FE, 3GR-FSE: Remove the DEFOG relay from the engine room No. 1 relay block. Disconnect the A7 ECM connector. Measure the voltage according to the value(s) in the table below. Standard voltage Tester Connection Condition Specified Condition Relay block DEFOG relay terminal 1 - Body ground Engine switch on (IG) 11 to 14 V Relay Block DEFOG relay terminal 5 - Body ground Always 11 to 14 V Measure the resistance according to the value(s) in the table below. Standard resistance Tester Connection Condition Specified Condition Relay block DEFOG relay terminal 2 - A7-13 (RDEF) Always Below 1 ohms for 1UR-FSE: Remove the DEFOG relay from the engine room No. 1 relay block. Disconnect the A7 ECM connector. Measure the voltage according to the value(s) in the table below. Standard voltage Tester Connection Condition Specified Condition Relay block DEFOG relay terminal 1 - Body ground Engine switch on (IG) 11 to 14 V Relay Block DEFOG relay terminal 5 - Body ground Always 11 to 14 V Measure the resistance according to the value(s) in the table below. Standard resistance Tester Connection Condition Specified Condition Relay block DEFOG relay terminal 2 - A7-35 (RDEF) Always Below 1 ohms NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
  7. CHECK WIRE HARNESS (REAR WINDOW DEFOGGER - RELAY BLOCK AND BODY GROUND) Disconnect the U20 and V20 defogger connectors. Disconnect the DEFOG relay from the engine room No. 1 relay block. Measure the resistance according to the value(s) in the table below. 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 NG --> REPAIR OR REPLACE HARNESS OR CONNECTOR OK: Go to next step
  8. INSPECT REAR WINDOW DEFOGGER WIRE Turn the engine 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 but gradually increases 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 A/C AMPLIFIER ASSEMBLY (A/C ECU) OK --> REPLACE ECM

See also:
• ON-VEHICLE INSPECTION

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