sum guy

iTrader: (4)

Like the tittle says I have a 99 truck pcm and I am trying to wire a high and low fan with it. Tuned the pcm to use both. Wired it like the camero: Blue connector pin #42 for low fan and red connector pin #33 for high fan. My low fan comes on, works great. The high fan pulses ground at all times, truck uses that pin for recirculation door. So my question is what pin would power the high fan on a truck pcm? Thanks for any help.

SSjon

iTrader: (4)

All of the info I have found on this is very unclear. So I am in for a good answer also.

6.0Nova?

I think it has something to do with the OS in the PCM...some of them aren't set up to trigger fans.

sum guy

iTrader: (4)

What is OS? I have it running one fan already, didn't know if you cought that.

G-Body

iTrader: (4)

Your PCM operating system is still setup to control the air recirc door. If your using HPTuners to tune it go to system>A/C>recirc option and set it to fan #2 instead of AC Recirc. Your wiring is correct, its the PCM tune thats off.

sum guy

iTrader: (4)

I tried to do this. I went in the editior to systems-ac and my only options were able and disable rpm and tps. Not sure why I cant get to the Recirc option?

bonestock_442

iTrader: (1)

I have this same issue. Pulses only.

brewster240

iTrader: (1)

the 99 truck used a mechanical rad fan.

i know when guys do the e fan conversion on the trucks they buy a harness setup from a few tuners.

G-Body

iTrader: (4)

What version of HPTuners are you using? Might be only in the newer versions. I`m on 2.23.211 Beta

96gt4.6

iTrader: (5)

Listen to this guy, he's right.

E-Mail Bill@hptuners and have them give you a link to download the newest Beta version. You will have a ton more options, including the one you need to get rid of the stupid pulsing output. Your screen, should look like this:



LOTS of new toys in the Beta version. They really need to update the current version with some of the goodies.

Your PCM will work fine after flashing the recirc option to Fan#2, or you can do as others have instructed and write a newer OS on as well, as long as it's the proper OS for your PCM.

the_merv

iTrader: (88)

The Beta has some nice stuff..I'm using that too.

So if you un-pun the AC Recirc Door and move it to Fans what will that do?

Is that Pin the one that controls the Vent?

96gt4.6

iTrader: (5)

Yes, you use the recirc door output for your Fan#2 control.

On the older trucks that do not have Efans, you will use pins#:

C1 (Blue) Pin # 42 = Low speed ground switched output.

C2 (Red) Pin # 33 = High speed ground switched ouput.

On the old version of HP tuners, you can switch the drop box to 2 fans, but when the 2nd fan comes on the output constantly cycles. With the Beta version of HP you can switch that fan #2 output to constant like the low speed output pin has, problem solved.

Be aware, not all versions of Beta are the same. They are constantly updating it with new features, but you will not know until you download, open and look around it it. I had an old version of Beta that didn't have ANY of this stuff in it. I found out by poking around on the HPTuners bulletin board that if you downloaded the newest version they had improved it yet again.

To the OP, get the latest Beta version and you'll have no problem using that PCM for 2 fans.

the_merv

iTrader: (88)

K..so what will happen on the truck if you remove that wire? The recirc/outside air door wont work?

96gt4.6

iTrader: (5)

No the recirc door will still function when you remove and sever that wire and use it for fans. Electricaly it's spliced into the recirc door activation circuit coming from the HVAC module. I belive the reasoning for the PCM being spliced into the recirc is for failure effects management mode. Basically, if the truck is starting to enter an overheat condition and the A/C is on, the PCM will command the recirc door to close. This will reduce heat load on the A/C system by not having to cool the hot ambient air from the outside, instead cooling the already cool cabin air, and by doing so keeping less heat being shed from the A/C condensor, which in turn puts less heat into the radiator.

Just my thoughts on why it's wired that way. But, electrically the A/C recirc will still function if this wire is depinned from the PCM.

the_merv

iTrader: (88)

Ah ok.

MillsMotorvation

Great info here. Time for HP tune Beta.

sum guy

iTrader: (4)

[QUOTE=96gt4.6;15542228]Listen to this guy, he's right.

E-Mail Bill@hptuners and have them give you a link to download the newest Beta version. You will have a ton more options, including the one you need to get rid of the stupid pulsing output. Your screen, should look like this:



LOTS of new toys in the Beta version. They really need to update the current version with some of the goodies

Great!! So is the HP update free?

96gt4.6

iTrader: (5)

[QUOTE=sum guy;15549501]Yep, just give them an email sent to support@hptuners.com or bill@hptuners.com if I recall correctly. They will provide you a link on your login/customer access page with the beta link, free!

You will like Beta, it's a LOT better than the current version that hasn't been updated in like 4 years. They are always updating Beta so just because some of you guys might already HAVE beta, doesn't mean you got the most current version. This was what happened to me, and how I learned of it.