Is it okay to Bypass the ECT Fan Switch?

1999 TOYOTA CAMRY
180,000 MILES • 3.0L • V6 • 2WD • AUTOMATIC
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MATROVSKY
  • MEMBER
  • 1 POST
Vehicle is overheating because the fans aren't coming on. They work if the A/C is on or when wired directly to the battery, but don't come in as the engine gets to temperature. If I unplug the ECT switch (pictured), the fans run fine. I assume that's because a failsafe is kicking in when it detects a circuit fault.

I've ordered a replacement switch, but it'll take some time to arrive. Am I okay to drive the car in the meantime with the current switch unplugged? The fan will run constantly while the engine is on, but will that cause a problem or break anything? My instinct says the only thing the ECT does is prevent excessive wear to the fans, but I don't know what I don't know, you know?
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Aug 4, 2023 at 10:36 AM
Repair Safety Notice: This information is for general instructional purposes only. Vehicle repair can be dangerous. Verify all information, follow manufacturer service procedures, use proper tools and safety equipment, and consult a qualified repair shop when needed.
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STEVE W.
  • AUTOMOTIVE REPAIR CONTRIBUTOR
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The ECT also tells the computer the coolant temperature so it can calculate the fuel profile as well as control the fans. With it unplugged you will end up with a few codes but the ECM should use the intake air temperature as a substitution but it won't be fully correct so your engine may operate a bit strangely from what you normally have.
With the fans running full time you may also get codes for the engine not warming up properly and it will run colder than normal.
Aug 4, 2023 at 7:56 PM
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