Question on how the OEM fan switch works. I am working on a custom (simplified) fan setup for my car and was wondering how the OEM fan switch works. I am wondering if it works by simply grounding the circuit. If so I am planning on using it to trigger a relay to kick on my fans from my rad and oil coolers.

Please no comments on "why are getting rid of the stock fans..." this was already covered in another thread.

Thanks!

 

Looking at the factory wiring diagrams for the FD, there are 3 switches to ground/trigger the 4 stock fan relays. Each of those switch ground their respective relay(s). All relays have their power come through the 15A METER fuse.

 

Cooling Fan Modification

 

I removed all of the OEM relays so I could just use one of these triggers to trigger my new relay for my aftermarket fans. Which color wire is the trigger for the OEM relays?

 

If you're talking about the single wire switch on the back of the waterpump/thermostat housing then yes. It has continuity to ground when the temperature threshold is reached.

 

That is the exact switch I was talking about. I run the FC switch and was going to use that as a trigger for my relays to turn on my fans.

 

You are looking at cooling fan relay #3 for that wire...

gotcha... the color of that wire is B/R (EM) -> L/G (D) -> L/G (F) to the relay.

It passes through the X-14 connector under the dash... and back through X-07

here is the page from the manual:

 

^ Holy hell this is awesome! Thank you!!!!