Could use some help on a 2004 Silverado fan question

[Chevy366]

GM list price now is $540 ... lowest published price (for an original GM part) is $340.

Holly crap! I knew they went up but geez.

[bronkx1]

I have both PCM connectors 33 and 42 in place so my harness is not like you describe with the green ac trigger. I have
enabled both fans and it seems to work just fine now. I was asking for tune help as this is a tune forum. I needed
to know what all needed turned on. I used a stock 2006 tune and just copied all the fan settings over and it
was good to go. I am not crazy about the Nelson harness either but new OEM is a lot of cash so until I can pull
the harness and fuse/relay box in a junk yard it will have to do.

[Chevy366]

Use the stock 06 settings, they work fine.
On the Nelson harness pin 42 gives fan 1,2 both in series at half power, and then with the other ground it runs fan 2 at full power, I wanted fan 1 at full power temp and A/C trigger and fan 2 at full power with fan 1 at full power when temp warranted it.
Thus I had to shift some wires around and to make that happen, ran the modified Nelson for a while until I got the stock harness. There is not but a few wires that need to be changed to make it act like the factory harness of fan 1 full power and fan 1 and 2 at full power when needed, the fan 1 and 2 half power are throwbacks to the old small fans used in cars not the larger higher output truck fans.