Rear Window Defogger System Does Not Operate

WINDSHIELD / WINDOWGLASS: WINDOW DEFOGGER SYSTEM: Rear Window Defogger System does not Operate

Rear Window Defogger System does not Operate

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.

WIRING DIAGRAM

INSPECTION PROCEDURE

PROCEDURE

1. CHECK OPERATION
(a) Check that the engine starts normally.
OK:
Engine starts normally.
NG -- GO TO SMART ACCESS SYSTEM WITH PUSH-BUTTON START
OK -- Continue to next step.
2. PERFORM ACTIVE TEST USING TECHSTREAM (REAR WINDOW DEFOGGER)
(a) Using the Techstream ACTIVE TEST, generate a control command and then check that the rear window defogger operates.

Air Conditioning Amplifier (A/C ECU)

Result

B -- INSPECT FUSE (DEFOG, AM2, LH-IG)
A -- Continue to next step.
3. CHECK OPERATION OF MULTI-DISPLAY WITH NEW OR NORMALLY FUNCTIONING MULTI-DISPLAY
(a) Temporarily replace the multi-display with a new or normally functioning one.
(b) Check that the malfunction disappears.
OK:
Malfunction disappears.
NG -- REPLACE AIR CONDITIONING AMPLIFIER
OK -- REPLACE MULTI-DISPLAY
4. INSPECT FUSE (DEFOG, AM2, LH-IG)
(a) Remove the DEFOG fuse from the engine room No. 1 relay block.
(b) Remove the AM2 fuse from the main body ECU RH.
(c) Remove the LH-IG fuse from the main body ECU LH.
(d) Measure the resistance of the fuses.
Standard resistance:
Below 1 Ohms
NG -- REPLACE FUSE
OK -- Continue to next step.
5. INSPECT DEFOGGER RELAY (Marking: DEFOG)

(a) Remove the defogger relay from the engine room No. 1 relay block.
(b) Measure the resistance of the relay.
Standard resistance:

NG -- REPLACE DEFOGGER RELAY
OK -- Continue to next step.
6. CHECK WIRE HARNESS (DEFOGGER RELAY - ECM AND BATTERY)

(a) Remove the defogger relay from the engine room No. 1 relay block.
(b) Disconnect the A53 ECM connector.
(c) Measure the voltage of the wire harness side connectors.
Standard voltage:

(d) Measure the resistance of the wire harness side connectors.
Standard resistance:

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
7. CHECK WIRE HARNESS (REAR WINDOW DEFOGGER - DEFOGGER RELAY AND BODY GROUND)

(a) Disconnect the U20 and V20 defogger connectors.
(b) Disconnect the defogger relay from the engine room No. 1 relay block.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.
8. INSPECT REAR WINDOW DEFOGGER WIRE
(a) Turn the power switch ON (IG).
(b) Turn the defogger switch ON.

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.

(d) Place the voltmeter's positive (+) lead against the defogger wire on the battery side.
(e) Place the voltmeter's negative (-) lead with the foil strip against the wire on the ground side.
(f) Slide the positive (+) lead from the battery side to the ground side.
(g) 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 -- Continue to next step.
9. CHECK OPERATION OF ECM WITH NEW OR NORMALLY FUNCTIONING ECM
(a) Temporarily replace the ECM with a new or normally functioning one.
(b) Check that the malfunction disappears.
OK:
Malfunction disappears.
NG -- REPLACE AIR CONDITIONING AMPLIFIER (A/C ECU)
OK -- REPLACE ECM