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fan relay wiring for ka question

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so I'm almost done with my ka24de swap, and

I'm setting up my relays and wiring (thanks to icehouse for the diagrams)

and as I'm wiring up the fan relay, and looking at the pinout diagram for the ecu, I saw 2 fan relay wires


my question is, has everyone independantly wired their fan relays with a grounding temp switch, or used the factory sensors and ecu? and does the ecu control power and ground to power up the relay? or are there 2 relays? and it only. controls power supply? or ground?


I think working on german cars all day might be causing me to overthink this.

dang bavarians!

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I've never tried to wire the fan the outputs on the ECU. From the drawing they look like AC fan relays. I'm not sure why they turn on. Do they only turn on when the AC is on? What temp do they turn on? We normally get a S12 inline temp switch or an aftermarket controller (Or megasquirt). My guess is the ECU ouputs are low side switched though. Let me know what you find out if you decide to do some testing :) I've always wanted to.

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thanks icehouse, really appreciate it.


I will play with it. I believe its pin 13 and pin 14, I'll check when I get home. but the ecu gets 2 coolant temp signals, 2 pin is definitely for ecu input, single wire probably for the guage, and I know on the s14 it controls the relays,typically they have a relay for the ac to switch the fan on when activated, or switch on a seperate fan if its equipped. I'm going to look up wiring schematics (so glad I have mitchell 5 at home)whether its ground controlled like bmws or positive side controlled like most domestics is what I'll have to find out.and I was thinking it might control both sides of the relay to energize it. hopefully I'll get a chance this weekend to tinker with it. but with it being easter, its a 50% chance

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great job SSSR20DET!!


So it only controls ground side of the relay. so I don't have to add anything to the motor, I'm guessing ine is for ac and one is for temp. I'll be wiring it this weekend hopefully, and double check, but if that diagram is right, it should work perfectly, and if controls the ground side, I can splice them together so there's no guessing which one is which.(I'll probably mess with it anyways and figure it out) but that's perfect. I was going to actually leave my relay to battery positive initially, that way the sensor would ground the circuit until it cooled off, even if I parked it and left. just so it doesn't heat soak.


man, I'm really excited now.

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Jeremy, will you look at alldata for a 91 infiniti M30, and see if the ecu has any thing like that for fan control? That is the harness that i am using. I am pretty sure that it only has one fan control for the A/C auxillary fan, as the motor had a mechanical fan.

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