Cooling fan circuit

[Bryan]

I have a 2000 Honda Odyssey.About a month ago, the mil came on for a code P0482(Cooling Fan 3 Control Circuit Malfunction). I checked all fuses,Condenser fan relay,radiator fan relay,and the radiator fan main relay.I started the van,and about a minute after turning on the ac, the fans came on.i shut off the ac,and shortly after the temp guage showed normal operating temp,the fans came on again.since the van wasnt overheating, and I didnt find anything, I decided to just erase the code to see if it would come back. Everything seemed fine until yesterday,the light came on again,only this time I got a code P0841(Cooling Fan 2 Control Circuit Malfunction) I did not check either of the fan switches, because I figured those would turn the fan on, on their own, not computer controled. I want to check the circuit again for bad connections, opens or shorts, but can anyone tell me what cooling fan 3 or cooling fan 2 means, and what circuit I should check? There are only 2 fans, but there are 3 relays,so maybe each one of those is a circuit? maybe there is something common (such as a ground) that both cooling fan 3 circuit and cooling fan 2 circuit share? Also, I have a small leak(either the thermostat gasket or leaking hose clamp from what I can tell) and the reservoir is empty,and the level in the radiator is just a little low. I was wondering if this could have anything to do with it,maybe because the computer uses the coolant temp sensor to see if the temp goes down after the ecm commands the fan on? Any help would be appreciated!

Topic

[619DioFan]

do a resistance test on the coolant temp sensor. if out of specs change it. these can cause this prob.

[college man]

p0482- cooling fan 3 circuit malfunction.I would top off
your coolant.that could be affecting the sensor.

p0841-transmission fluid pressure sensor/switch A circuit performance.

http://honda-tech.com/showthread.php?t=2613073

check the transmission fluid.if full and no delay
in transmission engagement.Then the sensor may be
faulty.

[Bryan]

Thank you for your replies. Drove the van all day today, temp gauge seems normal. I will top off coolant tomorrow and wait and see if code returns.
Just out of curiosity, does anyone know if its the coolant temp sensor that checks the coolant temp once the computer commands the fan on to set the code(P0841)?
If so, this would make sense seeing that the coolant level is low, and may be lower than the coolant temp sensor.

[EricTheCarGuy]

In addition to topping off the coolant I would recommend you bleed the air out of the system. If you have a small leak as you describe air can get into the system and possibly cause issues with the coolant temp sensor.

Keep us posted.

[Author]

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