Guys, I did my fans yesterday. LS1 fans, home made wiring with 2 relays (cheap and easy). Still have questions:
On the truck, (unlike the cars) I only use one pin?
So does that mean that BOTH fans will come on instead of just one?
I can't have a high/low?
Also, my tuner and I can't find why, but the fans are coming on with the truck, instead of waiting on temperature. Basically, the pin is grounded by default. What's the deal with that? Anybody have any ideas on where to find the settings that I'm missing? Thanks.

 

You can get High/Low settings with a single wire if you use a 3 relay setup.
Which pin on the pcm did you connect too?

 

you need 3 relays. 2 are for high, and one is for running on low.

here's the diagram

 

https://www.performancetrucks.net/fo...d.php?t=397117

You might read through this thread also for a discussion on the efan wiring.

 

So anybody know what we could be missing in HPTuners that is commanding the fans to be on when the truck starts?

 

If the fans come on when the truck is at a cold startup either your enable temp is really low or the a/c is on I think.

 

That's the thing. Neither of those is occurring. AC is off, and temp is sky high. Is anybody enabling these with HPTuners? Or is everybody using EFI Live?