Cooling fans not working?

2004 TOYOTA CAMRY
210,000 MILES • 2.4L • 4 CYL • 2WD • AUTOMATIC
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2004 CAMRY
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The car listed above is an XLE model, and the cooling fans will not work when the car is reaching about have way heat on the gauge and will continue to overheat.
I tried diagnosing the problem but couldn’t find the problem I check and relays and all work, have check all fuses and they work, I have changed the coolant temperature sensor and still didn’t work, the fans only work when I unplug the connector to the coolant temperature sensor and the connector has a voltage of 5.03 volts. I have also checked the power circuit to the fans, and everything is running the way it needs to be. I have checked the circuit from the fan relay fuse all the way to the coolant temperature switch and right I am at loss of what to do.
Jan 7, 2023 at 2:00 PM
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JACOBANDNICKOLAS
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Hi,

Do you have a scan tool that can actuate the relays to turn fans on? If you do, have you tried that and what were the results?

Also, take a look at the diagnostics below and let me know if you have already done all of these tests. It sounds like you have done a lot already. I just want to confirm.

Let me know.

Joe

See pics below.
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Jan 8, 2023 at 9:36 PM
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2004 CAMRY
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I have used all the info you provided and more and all have is a multi-meter and wires.
Jan 9, 2023 at 4:05 PM
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JACOBANDNICKOLAS
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Hi,

If you used the info above and everything checks good, then you must have an open circuit between the relays and the fan motors, the ECM is failing, or we have no ground paths for the motors or relays.

I attached the wiring schematic for the radiator fans. Take a look through them. I highlighted grounds, fans, and relays. If you have already checked power supplies, then we should confirm continuity to ground.

Let me know what you find.

Joe

See pics below.
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Jan 10, 2023 at 4:28 PM
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2004 CAMRY
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Hey,
I have been checking for ground recently and recognized that relay fan 1 has negative output for both prong 1 and 2 but when I put the key in the on position, they both turn positive output is that normal?
By the way I got a used ECU from the same car and used it the car ran just fine but had the same problem with the fans. And the fans only turn on when I unplug the connector from the ECT sensor, but the car will run unstable and cannot shift into third gear.
Jan 15, 2023 at 12:59 PM
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JACOBANDNICKOLAS
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Hi,

When you say negative voltage, that indicates the polarity (battery power) is running in the opposite direction. Is that what you mean? Is that at all relays? I ask because there is a diode between the two relays that should only allow power to go in one direction. However, I don't think that is causing it.

The diode is between relays 2, and 3, with pin 2 on each. If you switch your test lamp or meter, does it do the opposite?

Joe
Jan 15, 2023 at 6:41 PM
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I meant that positive is live as in red for live and negative is ground as black for ground and also, I have replaced the ECT sensor to get that out the way. I don’t know if all do that, I will be at it tomorrow and see. But I don’t think so.
Jan 15, 2023 at 10:52 PM
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2004 CAMRY
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Hey,

I checked the relays today and saw that only relay fan 1 does that and when I remove relay fan 2 and 3 it goes back to normal with one side being live and the then ground. So, what does that mean? By the way my ECU been clicking like crazy when I start the car it sounds like a hard drive rewriting thing.
Jan 16, 2023 at 11:25 AM
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JACOBANDNICKOLAS
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Hi,

The ECU is clicking? Do you mean one of the relays?

Joe
Jan 16, 2023 at 4:38 PM
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No I am pretty sure it is the ECU because I hear it in the cabin when I drive it is pretty annoying it sounds like a computer hard drive.
Jan 19, 2023 at 4:35 AM
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JACOBANDNICKOLAS
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Hi,

Okay. Do you plan to replace it yourself? If you do, make sure the key is in the off position, then disconnect the battery negative cable. (See directions below)

Let me know how things turn out for you.

Joe

See pic below.

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Jan 19, 2023 at 4:32 PM