5.0 Eater

iTrader: (8)

Ok I wondering if anyone has done this and if they had could they give me a little help. So I converted my 2002 GMC to electric 05 fans and hooked it into the computer through a Nelson harness... What I'm wondering is there a way i can override the harness with a switch I'll run into the cab so that I can turn on one/both fans before the computer turns it on. Looking to tap into the harness instead of rewiring with relays and so forth... Has anyone tried this before? Please help me out if you have and thanks in advance for the help.

BLKSSLTT

iTrader: (12)

why not just adjust fan on off temps in the tune?

5.0 Eater

iTrader: (8)

^^ Well I could do that but would rather be able to switch it on earlier if I could without always having to adjust the tune to change the temp activation... If there is a simple way to tap into the harness and add a switch that would be great and get me what I need. Appreciate the help!

BLKSSLTT

iTrader: (12)

find your power supply for the fans, tap in and run a wire to a relay. Run from the relay to a switch and run the power to the switch off any constant power on the truck. Throw a fuse in there for good measure. To check to see which wire is the power for the fans, plug in the harness as per instructions. Make sure it works as it should. With the truck running before the fans come on, test to see which wires have power and which dont. then once they come on, see which wire is the feed for the fans as it will have power at this point.