KySilverado

iTrader: (7)

Can anyone confirm that pin 33 of an 03 PCM will control HIGH Speed of electric fans? I need to re-do my nelson wiring harness. May as well get the high speed control to the PCM if it works.

TIA for any info.

BlackGMC

iTrader: (31)

I am pretty sure the 03 and 04 are the same. I did it on my 04....

Here is the thread.
https://www.performancetrucks.net/fo...ighlight=efans


Hopefully your using EFI Live, cause HPtuners does not have the AC pressure adjust needed to control the second fan correctly....
http://www.hptuners.com/forum/showthread.php?t=8858

Truckshop

iTrader: (17)

my 04 computer does. just know that it comes on in addition to pin 42. the pcm turns the first one on for low and both for high.

KySilverado

iTrader: (7)

Thanks Corey, I do have HPT this and a couple other things make me wish I had gone with EFI Live. I'll try it and it will be what it is as far as the AC control pressures. Guess I could put in a manual switch if it if the AC starts getting hot in traffic or something.

Went through your thread also. I have the exact wiring diagram printed out.

BlackGMC

iTrader: (31)

No problem man, check out this post on the HPTuner thread I posted.

KySilverado

iTrader: (7)

Time to tear something up.

BlackGMC

iTrader: (31)

SWEET!! So you got one of the new development tunes? I logged AC pressures to get my AC really cold, the factory 05+ settings don't get the AC that cold IMO... Post up on how you like it

KySilverado

iTrader: (7)

Yeah a beta version. E-mailed support@hpt per the thread you posted. Bill had it sent back in like a day. Now if I can get my transient fueling I requested 3 months ago I'd be perfectly happy I put the AC PSI identical to yours to start. I like cold AC. It will be a while before I get them hooked up. But will post up when I do. Have to make a new or re-do the harness. Not real motivated right now.

Atomic

iTrader: (42)

Yep, pin 33 is high, which I think is already covered here. You mentioned putting in a manual switch, thats what I did with my installation. There is a switch on my dash, and if I push it one fan will turn on high regardless if the engine is on or off. If both fans are on low anyone, then both will turn on high. I did this by using a fourth relay in addition to the 3 already in the diagram (made my harness exactly the same way). I can connect the other fan to the relay no problem if I want both on to cool off the engine bay if im going to work on there simply by connecting the other way to the 87a pin of the relay.

Good luck

BlackGMC

iTrader: (31)

That is some great customer service! BTW do you need another PCM pin, i have a few extra.