Is it okay to Bypass the ECT Fan Switch?

MATROVSKY

MEMBER
1999 TOYOTA CAMRY
3.0L
V6
2WD
AUTOMATIC
180,000 MILES

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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1 Reply

STEVE W.

MECHANIC
13,003 POSTS

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.