miller white

iTrader: (2)

Just got some ls1 fans for my 04 rcsb. I know everyone says go with nealson wiring harness's. But I know there are some harness guys on here have built and work just as good. Anyone have a diagram of a good set up? Thanks.

neilownz

search and you should find some diagrams of the nelson one. 2 relay is without a/c and 3 relay would be with a/c turn on.

SilverDog

I used the diagram that is posted. It is the (SLIGHTLY MODIFIED) 05+ GM diagram so I would use it over all other diagrams. Doesn't work off the Nelson style A/C switch but off pins 42 and 33 which I recommend since you truck is a 2004(like mine). I have posted in several threads with electric fan info plus created some. https://www.performancetrucks.net/fo...d.php?t=437058

neilownz

I still havent gotten mine working. I think i might try just putting that blue pcm wire from the nelson harness to one of those cylinder head sensors. Might have blown a relay too, but if you are using ls1 fans it shouldnt be a problem.

Anyways it would be tough to build a harness for less than 100 bucks... plus the time hassle.

Atomic

iTrader: (42)

this is the one i used



I added the bottom part if you want to do it manually

cost of making my harness was about $40 for all the parts, took about an hour.

nonnieselman

iTrader: (10)

that last 5 harness's ive put together worked just fine off that diagram above.. but i modified it for the Pin 42 and 33

miller white

iTrader: (2)

still completely lost guys....

SUX2BU

iTrader: (14)

Yeah, i should have built my own. Mine has messed up twice now.

Atomic

iTrader: (42)

Made a slight change to my diagram, the middle wiring for the switch should be ground, not 12v. I remember I had to do that when I installed it, but never changed my diagram.

miller, its really not hard man, just follow the lines and connect the dots.

miller white

iTrader: (2)

Ok I'm gonna go for it tonight. Thanks guys!