I have an aftermarket fan controller which works fin but its wired directly to the battery. So the fan stays on until the radiator temp goes down and lately it has been draining my battery. So I would like to wire it to an ignition wire, so it will only be on when my key is on.

Is there a convenient wire under the hood of my 91 z28 5.7, that I can splice into for this?

 

get a hayden adjustable temp sensor works great runs off fan relay ground wire only.EZ

 

This is not helpful lol. I already have one im just looking for a wire thats hot when the key is on under the hood.

 

The best way is to run a wire from the fuse box out to where you need it.

 

Thats what I was thinking I was just hoping there was an easier way, thanks!

 

You may already know all this but here is how I run mine. Test some of the slots in the rear of the fuse block for key "on" power only. Then you can use a male spade connecter in that slot. Run that wire to one side of the new relay then install your controller on the ground wire coming off of the other side. That way your using very low amperage through the controller. Use the battery terminal mounted next to the battery for power to the fan then through the relay to ground on the other side and install the probe about 2in below the upper radiator hose through the fins.
Here's the exact circuit with relay. I have two of these. One for each fan.