So I'm looking to control my 2 fans through my Holley HP EFI. Currently they're controlled by a Painless F5 controller, but I keep reading about people having failures, and honestly, I like "simple" whenever possible.
I've got the control side of things figured out in the Holley software, and it's a ground controlled circuit. I'm guessing that means that when temps reach my preset limit, the Holley grounds the circuit/relay to turn on the fans, as opposed to using 12v to do so. Correct?

Can anyone show me a relay diagram of how I would wire the fan relays? There are two, but let's just stick with one for simplicity sake. -or heck, just point me in the direction of a relay I should purchase???

I don't need a kit per se, with a temp sensor as it's being controlled by the Holley, which already reads temp. Just need that relay and a diagram.

 

You will need two separate outputs on the Holley ECM to run two fans. Do you have two outputs available? And what kind of outputs are they?

You can set up the outputs to be a 12 volt source or be a sink to ground, depending on the spec of the outputs that are still available to use.

 

Yes, I have 2 available. I can set them up as either 12v or ground. I've got all that figured out, I'm looking for the relay side of things. -I'm not sure what relay to purchase and how exactly to wire it.

 

you can use a relay such as this (need 2, 1 per fan)

https://www.summitracing.com/parts/spu-ix-frh/overview/

the output side of the relay power from battery through the fuse to the common output side of the fan relay. the other normally open output side of relay to the fan (make sure to pick the right fan wire for correct fan rotation). the other fan wire to good ground.

the coil side of the relay goes to your holley HP output driver. you could do either b+ or gnd driver

you can easily mount the two relays on the radiator support type bracket coming up the side in the battery tray area (either side)

 

This may be a dumb question but.....the coil side needs a ground and a 12v, right? ...is what I choose for the output what determines which side of the coil the Holley connects to? I've never configured the ECM before, and never had that choice. Seems great to have choices but I know MOST times when power and ground are involved, it's best not to have that backwards.

 

yes, one side of the coil will ultimately have 12v power to it and the other side will be connected to ground... when that happens the coil will function... ie the normally open contact will be connected to the common contact and the fan will turn on. when either 12v or gnd is taken away from the coil the normally open contact will re-open

you need to look at the actually relay you buy to see if the coil has a required + and gnd side (the coil itself doesn't care but a lot of times in parallel with the coil their can be a diode to suppress transient voltage that occurs when the power is removed)

with the holley (i haven't used holley HP yet, but soon) my understand is the output driver can be configured to either be a high side driver, ie when it turns on it provides 12V feed, or a low side driver, ie when it turns on the output pin of the holley will be a ground connection.

therefore however you configure your holley output, that output will go to one side of the coil and on the other side of the coil you will tie it to the opposite type connection... ie if you have your holley outputting 12v when it turns on you would connect the other side of the coil to ground

think of the holley output like a light switch with the switch being inside of the holley. one side of the switch in the holley is tied to either 12V or gnd depending on how you configure it. the other side of the switch is the output pin on the holley

 

Gotcha. That all makes sense. Thank you.