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.
Window Defogger System: Inspection
- INSPECT AIR CONDITIONING CONTROL ASSEMBLY
- Auto air conditioning:
Inspect operation of the defogger timer.
- Connect the positive (+) lead from the battery to terminal A3-3 and the negative (-) lead to terminal A4-6.
- Connect the positive (+) lead from the battery to terminal A4-1 through a 1.4 W test bulb.
- Push the defogger switch ON, check that the indicator light on the switch and the test bulb light up for 12 to 18 minutes, and then the indicator light and the test bulb go off.
If the result is not as specified, replace the A/C control assembly.
- Disconnect the connector from the A/C control assembly.
- Check the voltage or continuity of each terminal of the wire harness side connector.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Standard
TERMINALS AND SPECIFIED CONDITION REFERENCETerminal No. Condition Specified Condition A4-6 - Body ground Constant Below 1 Ω A4-1 - Body ground Ignition switch Lock or ACC No voltage A4-1 - Body ground Ignition switch ON Battery positive voltage A3-3 - Body ground Ignition switch Lock or ACC No voltage A3-3 - Body ground Ignition switch ON Battery positive voltage If the result is not as specified, there may be a malfunction on the wire harness side.
- Auto air conditioning, with EMV & NAVIGATION system:
Inspect operation of the defogger timer.
- Connect the positive (+) lead from the battery to terminal 9 and the negative (-) lead to terminal 10.
- Connect the positive (+) lead from the battery to terminal 7 through a 1.4 W test bulb.
- Push the defogger switch ON, check that the indicator light on the switch and the test bulb light up for 12 to 18 minutes, and then the indicator light and the test bulb go off.
If the result is not as specified, replace the A/C control assembly.
- Disconnect the connector from the A/C control assembly.
- Check the voltage or continuity of each terminal of the wire harness side connector.
Standard
TERMINALS AND SPECIFIED CONDITION REFERENCETerminal No. Condition Specified Condition 10 - Body ground Constant Continuity 7 - Body ground Ignition switch Lock or ACC No voltage 7 - Body ground Ignition switch ON Battery positive voltage 9 - Body ground Ignition switch Lock or ACC No voltage 9 - Body ground Ignition switch ON Battery positive voltage If the result is not as specified, there may be a malfunction on the wire harness side.
- Auto air conditioning:
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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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