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Thread: Electric fan not kicking in

  1. #1
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    Electric fan not kicking in

    Need some help with my electric fan wiring. There were two plugs to the OEM fan, black and red and then pink and brown.

    I wired up my mishimoto fans like the diagram below using red and black wires
    These turned out to be for the AC as both fans kick in when it's turned on, all good. So I assume the other two wires were for the thermo fan circuit.

    However when I check them for voltage or continuity when the engine is hot I get nothing. If I attach my power probe negative to the brown wire and check the pink I get no lights, if I do this the other way around it shows negative. Therefore brown should be live and have a voltage to it when engine is hot.

    I have checked the marked fuses and relay on the diagram and all are fine. Any ideas as dont really want to run the AC when the car gets hot.

    When I was fiddling the brown and pink wires did touch and short out so I'm sure I have blown something just no idea what.

    Thanks bill

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    Wiring diagram used

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    Member R3K1355's Avatar
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    Why does it look like you're fiddling around with a temperature sender on your oil filter sandwich plate?

    Does your fan switch actually work? Have you tested or replace it?

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    No it's not from the sandwich plate, i just happen to have that mounted where the battery used to be.

    Someone has suggested the switch in the radiator so will check that tonight


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    does the ecu not tell the fans to switch on? i guessed it would use the engine temp sensor to know when to switch it. knowing Nissan it would switch the earth.

  6. #6
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    I think the ECU does send the signal when the engine gets to a certain temperature. I have a nistune board and I believe you can change the point at which the fan comes on or off.

    The stock one worked with the nistune before so it is obviously something i have done- will see tonight i guess.

  7. #7
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    These two plugs are under the inlet manifold as nothing is in the rad. I assume the single one (left) is the temperature sensor and the one on the right the switch?



    Temp sensor for single plug



    Double plug shows 4.8v with ignition on. One side shows negative the other shows neither.

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    Guest immy21's Avatar
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    Single is temp sensor for dash

    Double is temp sensor for ECU, 1 wire is 5v pull up from ECU, sensor is resistor then ECU measures the resistance (EDIT: by looking at the returned voltage) compared to 5v supplied.
    Last edited by immy21; 14-06-2019 at 18:17.

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    Right so then depending on what resistance the ECU sees will determine if it kicks the fans in or not.

    Chance that I've blown this when the wires shorted? Or something further up?

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  10. #10
    Guest immy21's Avatar
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    Yes but it's easy to check.
    On a cold engine open up Nistune then see if coolant temp is reading the same as outside temp.
    Then run the engine until hot watch coolant temp.
    Check what temp the electric fan kicks in, its quite high, like 90-95 iirc as Viscous is main cooling fan.

    Lower the kick in temp and test.

  11. #11
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    Ok so after a lot of messing about, it seems that my digital temp gauge over reads.

    I checked the ECU temps and also borrowed an infrared temp detector.

    Fans kick in at an indicated 98 on the gauge (bottom hose) and off at 88 which is actually 95 and 85 respectively according to what the ECU reads.

    Neither hose or rad ever went above 83 degrees with it idling on the drive

    So all is well, I just didn't have the balls to let it get that hot on the gauge. The two wires I shorted I now believe are for the AC pump as I have no cold AC (found that out after I didn't need to have heaters on flat out to help the cooling!!)

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  12. #12
    Guest immy21's Avatar
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    At least you figured it out.

    Do you have Nistune software and licence?
    Stock form the electric fan is used for overheating (and A/C), hence the high kick in temps.

    Since you have done away with the viscous (if I'm reading this correctly) I suggest lower the fan kick in temps.

    Iirc there are 2 settings, low fan speed and high fan speed.
    If your not sure what to do, ask and we can help you, alternatively ask your tuner to send send tweaked map for your electric fans, it's a 2 second job for them.
    Last edited by immy21; 24-06-2019 at 19:38.

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    Yeah still got the nistune and license.

    Yeah that makes sense instead of having the car run at its upper limits all the time. I'll have a look tonight!

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