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Electric fan ignition wire

Posted: Sun Dec 31, 2017 10:07 pm
by aaronlee133
Hey fellas, installing a SPAL fan harness and it requires I splice into ignition so that the fan doesn’t run while engine’s off.

Question: where is the best place to do so in the engine bay? I have the switch/harness positioned next to the coil pack but having problems locating the exact wire to tap into. Thanks Aaron

Re: Electric fan ignition wire

Posted: Sun Dec 31, 2017 10:27 pm
by shagymc
I'd recommend running a relay off of the ignition harness. It will make sure you have the appropriate amperage support needed to run fans.
30: Output to fan ignition
85: Fused ignition 12V
86: Ground
87: Fused 12V to battery

Just my two cents! Good luck!

Re: Electric fan ignition wire

Posted: Sun Dec 31, 2017 11:59 pm
by jondee86
If you are doing this, you just need to tap any wire that only has 12V when the key is ON.


So the easiaest one is most likely the 12V supply to the coil and igniter. That input
is just a signal and doesn't power the fan.

Cheers... jondee86

Re: Electric fan ignition wire

Posted: Mon Jan 01, 2018 3:30 pm
by aaronlee133
Thanks fellas and thanks Jondee so it seems straight onto the positive plug of the coil should do it. And correct that diagram you posted is the spal diagram provided.

Happy New Year everyone and long live the ae86! -Aaron

Re: Electric fan ignition wire

Posted: Wed Feb 28, 2018 7:47 am
by Kitsunami
I'm currently wiring up an electric fan and have opted to use the two-relay system in conjunction with the AE92 coolant neck with the sensor so I don't have to think about turning on and off the fan manually. But I need a little clarification. I've wired up my setup using this diagram:


However, I think I'm confusing some of the terms on the diagram.

Right now I have the lead labeled 'Accessory' hooked up to a 12V only when the car would be on, and the lead labeled 'Sending Unit' hooked up to the AE92 Coolant Neck Sensor. Is this actually the OPPOSITE of how it should be hooked up?

In other words, should 'Sending Unit' be 12v only when ignition is on, and 'Accessory' be the Coolant Neck sensor?

I tried testing my set up by hooking everything up to a battery and dipping the sensor in boiling water (Keeping in mind my Eight Six is still a ways out from being able to run), but no dice. When I grounded the lead labeled 'Sending Unit' WITHOUT the sensor plugged in, the fans fired right up.

If I have this wired up correctly, then maybe the AE92 neck sensor is just bad?

Thanks all!

Re: Electric fan ignition wire

Posted: Wed Feb 28, 2018 10:45 am
by jdm86gtz
If you are wondering if you mixed up pins 85 and 86 then no you are ok.
I have mine wired as above.

Re: Electric fan ignition wire

Posted: Thu Mar 01, 2018 6:06 am
by shagymc
This is going to depend on what your sending unit puts out when it reaches temp, if it sends a signal at temp. Senders typically work off of varying resistance on a ground line so the sensor will be 2-wire and the output lead will vary from low impedence to some higher value (whatever it is calibrated to) and that signal moves the needle in your cluster. If it has 3 wires and one wire sends a ground continuously above or below a setpoint, than this will work. If it is only a 2-wire, you'll need to look into a different option.

Re: Electric fan ignition wire

Posted: Thu Mar 01, 2018 6:11 am
by shagymc
Also, your diagram is drawn so that the sending units trigger wire (the wire that will show ground above/below a setpoint) drops ground at temp. So if it shows ground above the setpoint, you'll need to wire the first relay slightly different by moving the 87a wire to 87. Based on what you said in your post about being able to ground the sending unit wire and fans starting, it sounds like it is already wired this way so make sure to check those connections. Feel free to PM me if you have specific questions and I'll give you a FB name to message me at.