sreve

iTrader: (3)

hello
sometime back i put an electric fan on my '99 GMC nbs 5.3L . i am now in the procesess of learning to tune. i want to run the fans from the pcm it does support it. problem is i do not know which pins it enables as there are 30 of them not in use.
anyone been down this road before?
thanks

WorkTruc

iTrader: (8)

pin 42

gmforlife

iTrader: (2)

what work truck said, pin 42 runs the fans

sreve

iTrader: (3)

hey guys thanks for the reply. i asume thats on the c-1 blue,cause it's busy with the trans on the red one.
the def file does support two fans so there must be one other ground pin.
c-1#42 runs f-body low speed, same pcm differnt program as f-body uses c-2#33 for high speed, trucks use it for the recirc on hvac. i really apprieate the help. if there is there is the second pin i'm gonna find it.
i have a two speed fan set up off a crown vic, works slick but i know alot you you belive i'm going to hell because of it. won't happen i never drive it on sunday

negativeswitches

iTrader: (15)

not to be a turd but i know you can search and find exactally what you want

sreve

iTrader: (3)

i don't smell any turds and i'm pretty close, right across the river from you.
i spent a couple hours searching the fan threads and found that '03 &'04 use 33 and 42 pins. the '99 - '02 use 42pin. there are a few threads like mine asking the same question with no answer. tuner cats does support 2 fans on '99 - '02 but the posts from people that got nelson tune and harness for these trucks only use pin 42 if he could sell a two speed harness setup i'm sure he would.
thanks to all who replied