Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Inspection Procedure
- CHECK OPERATION
- Check that the engine starts normally.
OK:
Engine starts normally.
NG : GO TO
OK : Go to Next Step
- Check that the engine starts normally.
- 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)
ACTIVE TESTTester Display Test Part Control Range Diagnostic Note Defogger Relay (Rear) Operate rear window defogger OFF/ON - Result
RESULT CHARTResult Proceed to Rear window defogger operates normally A Rear window defogger operates abnormally B
B : Go to step 4
A : Go to Next Step
- Using the Techstream ACTIVE TEST, generate a control command and then check that the rear window defogger operates.
- 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
- 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 Ω
NG : REPLACE FUSE
OK : Go to Next Step
- INSPECT RELAY (DEFOG)
- Remove the DEFOG relay from the engine room No.1 relay block.
- Measure the resistance of the relay.
Standard resistance
RESISTANCE SPECIFICATION CHARTTester Connection Specified Condition 3-4 Below 1 Ω 3-5 10 kΩ or higher 3-5 Below 1 Ω
(when battery voltage is applied to terminals 1 and 2)
NG : REPLACE RELAY
OK : Go to Next Step
- 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
VOLTAGE SPECIFICATION CHARTTester 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
RESISTANCE SPECIFICATION CHARTTester Connection Condition Specified Condition Relay block DEFOG relay terminal 2 - A7-13 (RDEF) Always Below 1 Ω
- 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
VOLTAGE SPECIFICATION CHARTTester 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
RESISTANCE SPECIFICATION CHARTTester Connection Condition Specified Condition Relay block DEFOG relay terminal 2 - A7-35 (RDEF) Always Below 1 Ω
NG : REPAIR OR REPLACE HARNESS OR CONNECTOR
OK : Go to Next Step
- for 3GR-FE, 3GR-FSE:
- 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
RESISTANCE SPECIFICATION CHARTTester Connection Specified Condition V20-1 - Relay block DEFOG relay terminal 3 Below 1 Ω U20-1 - Body ground Below 1 Ω Relay block DEFOG relay terminal 4 - Body ground Below 1 Ω
NG : REPAIR OR REPLACE HARNESS OR CONNECTOR
OK : Go to Next Step
- 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 SPECIFICATION CHARTVoltage 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.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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