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 COMMUNICATION SYSTEM
- Select the DTC check on the intelligent tester to check for communication errors.
Result
COMMUNICATION SYSTEMNot output DTC codes A Output DTC codes (Multiplex communication) B Output DTC codes (CAN communication) C B: GO TO MULTIPLEX COMMUNICATION SYSTEM
C: GO TO CAN COMMUNICATION SYSTEM
A: Go to next step
- PERFORM ACTIVE TEST BY INTELLIGENT TESTER
- Select the ACTIVE TEST, use the intelligent tester to issue a control command, and then check the window defogger operation.
AIR CONDITIONER
AIR CONDITIONER ACTIVE TEST TABLEItem Test Details DEFOGGER RLY Turns rear window defogger OFF/ON Result
RESULT DESCRIPTION TABLEOK (with Navigation System) A OK (without Navigation System) B NG C B: Go to step 5
C: Go to step 9
A: Go to next step
- REPLACE MULTIMEDIA MODULE DISPLAY
- Replace the multimedia module display.
- CONFIRM REAR WINDOW DEFOGGER OPERATION
- Turn the engine switch on (IG), press the defogger switch, and check that window defogger operates.
NG: REPLACE A/C AMPLIFIER ASSEMBLY
OK: END
- REPLACE INTEGRATION CONTROL & PANEL
- Replace the integration control & panel.
- CONFIRM REAR WINDOW DEFOGGER OPERATION
- Turn the engine switch on (IG), press the defogger switch, and check that window defogger operates.
OK: END
NG: Go to next step
- REPLACE RADIO RECEIVER ASSEMBLY
- Replace the radio receiver assembly.
- REAR WINDOW DEFOGGER OPERATION
- Turn the engine switch on (IG), press the defogger switch, and check that window defogger operates.
NG: REPLACE A/C AMPLIFIER ASSEMBLY
OK: END
- PERFORM ACTIVE TEST BY INTELLIGENT TESTER
- Select the ACTIVE TEST, use the intelligent tester to issue a control command, and then check the DEFOG relay operation.
- Check that operation sound of the DEFOG relay is heard.
Result
RESULT DESCRIPTION TABLERelay operating sound is heard OK Relay operating sound is not heard NG OK: Go to step 13
NG: Go to next step
- INSPECT DEFOG RELAY
NG: REPLACE DEFOG RELAY
OK: Go to next step
- CHECK WIRE HARNESS (DEFOG RELAY - BATTERY POSITIVE)
- Disconnect the DEFOG relay.
- Measure the voltage according to the value(s) in DEFOG RELAY - BATTERY POSITIVE
.
Voltage:
Engine room No. 1 R/B, J/B
DEFOG RELAY - BATTERY POSITIVETester Connection Condition Specified Condition 1 - Body ground Engine switch on (IG) 10 to 14 V
NG: REPAIR OR REPLACE LH-IG FUSE OR HARNESS AND CONNECTOR
OK: Go to next step
- CHECK WIRE HARNESS (DEFOG RELAY - A/C AMPLIFIER ASSEMBLY)
- Disconnect the DEFOG relay and A/C amplifier assembly connector.
- Measure the resistance according to the value(s) in TESTER CONNECTION SPECIFIED CONDITION TABLE
.
Resistance
DEFOG RELAY - A/C AMPLIFIER ASSEMBLYTester Connection Condition Specified Condition 2 - J58-3 Always Below 1 ohms 2 - Body ground Always 10 k ohms or higher
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: REPLACE A/C AMPLIFIER ASSEMBLY
- INSPECT DEFOGGER RELAY
NG: REPLACE DEFOG RELAY
OK: Go to next step
- CHECK WIRE HARNESS (DEFOG RELAY - BATTERY POSITIVE AND BODY GROUND)
- Disconnect the DEFOG relay.
- Measure the voltage and resistance according to the value(s) in DEFOG RELAY - BATTERY POSITIVE AND BODY GROUND
.
Resistance:
Engine room No. 1 R/B, J/B
DEFOG RELAY - BATTERY POSITIVE AND BODY GROUND (RESISTANCE)Tester Connection Condition Specified Condition 4 - Body ground Always Below 1 ohms Voltage:
Engine room No. 1 R/B, J/B
DEFOG RELAY - BATTERY POSITIVE AND BODY GROUND (VOLTAGE)Tester Connection Condition Specified Condition 5 - Body ground Engine switch on (IG) 10 to 14 V
NG: REPAIR OR REPLACE DEFOG FUSE OR HARNESS AND CONNECTOR
OK: Go to next step
- INSPECT NOISE FILTER
- Disconnect the noise filter connectors.
- Measure the resistance according to the value(s) in NOISE FILTER
.
Resistance
NOISE FILTERTester Connection Condition Specified Condition A1 - B1 Always Below 1 ohms A1 - Body ground Always 10 k ohms or higher
NG: REPLACE NOISE FILTER
OK: Go to next step
- CHECK WIRE HARNESS (DEFOG RELAY - NOISE FILTER)
- Disconnect the DEFOG relay and defogger wire connectors.
- Measure the resistance according to the value(s) in DEFOG RELAY - NOISE FILTER
.
Resistance
DEFOG RELAY - NOISE FILTERTester Connection Condition Specified Condition 3 - Q21-1 Always Below 1 ohms
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: Go to next step
- CHECK WIRE HARNESS (DEFOGGER WIRE CONNECTOR - BODY GROUND)
- Measure the resistance according to the value(s) in TESTER CONNECTION SPECIFIED CONDITION TABLE
.
Resistance
DEFOGGER WIRE CONNECTOR - BODY GROUNDTester Connection Condition Specified Condition P19-1 - Body ground Always Below 1 ohms
NG: REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: REPAIR OR REPLACE REAR WINDOW DEFOGGER WIRE
- Measure the resistance according to the value(s) in TESTER CONNECTION SPECIFIED CONDITION TABLE
.
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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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