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Engine fan control with switch override


hachoo

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hey guys, i really need your advice. planning to change to electric radiator fan, i wish to control it through the ECU when it reaches temp and able to override with a switch if i want to turn it on too when i at the tracks. anyone able to guide me on this?

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It would be most common just to wire a switch to ground the relay trigger (independant of ecu), however if you want to do it in the ecu, then you can wire your switch to a DI and set it up like below.

This example would is assuming the Fan relay is connected to Aux 1 and the override switch is connected to DI1.  

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No.  DI1 is your switch, this item can have an on or off status.  Virtual aux 1 also has an on or off status, it will be on when the fan temperature/hysteresis conditions are met and off at all other times. 

Aux 1 is the output that controls the fan.  So we tell Aux 1 (the fan) to turn on if DI1 is on OR if virtual aux 1 is on.  

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  • 1 month later...

If your switch is connected to ground then the pull-up should be on, if the switch is connected to +12V then the pull-up should be off.

Active edge will have no effect for a switch.  

On level just inverts which switch position represents on or off.  If the switch works backwards then change the on level to the oposite.

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  • 6 months later...

I have my intercooler fan set up on Aux 5 as shown and it seems to work fine so far when I adjust the conditions to trigger the fan.  However, when I turn the key off, the IC fan turns on.  Where would I look to prevent the fan from coming on when I turn the ECU off?

 

image.png.bd6656d5bf0a8443b4ac9ac48c80295a.png

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This is a wiring problem causing a backfeed.  As per the manual and help file wiring diagrams, the 12V supply to your relay coil needs to be from an ignition switched +12V source.  

If it is not easy to change that 12V source and you have a spare ignition output then you could move the wire from aux 5 to an ignition output instead which is acceptable to have a constant 12V feed.

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Understood, and sorry for the newb question.  I appreciate the help!  I don't see any additional ignition outputs since I converted to coil-on-plug, so I'll likely have to make the change to switched 12V for the relay.  I'll lose some functionality (vehicle off, IC fan overridden to "on") for my override switch, but that's not the end of the world.

Just for my further understanding (sorry, this is my first time doing the full wiring and setup), it's only the ignition outputs that can control a constant 12V feed, not the injection aux outputs, correct?

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