InchUp

iTrader: (2)

I can get any PCM that will control the things I need for $45 at the local parts yard, but I'm not sure if I were to upgrade to an '02-'03 PCM if all the wiring would still work with my custom harness. If the '01 PCM controls a single fan, I am content then, and I'll have to hardwire a controller to come on when the A/C is.

No biggie, just thought I could get out of some work by tuning rather than wiring.

7845

iTrader: (1)

you should be fine with the wiring diagaram i gave you. it will work 2 fans. your 01 tahoe will control it as well. if you wanted you can have that pcm reflashed as a truck one which either will still control the fans

InchUp

iTrader: (2)

When it comes to wiring I am totally lost unless I have someone physically show me what I'm doing, it's just a weak point in my understanding. How would I go about modifying that dual fan diagram to run dual speeds on a single fan, because I really like that idea to have a low and high, all controlled by the PCM. I have a single 18" electric fan from a Lincoln Mark VIII shown here, I think I can handle the A/C e-fan myself now as a stand alone but now that I read there's an actual way to run 2 speeds on this 18" fan, I'd like to. Before I was just going to have it on and off, no in between.

Here's the fan, radiator and brackets all mocked up on the core support. I have a red wire, yellow wire and black wire, all the same thickness coming from the pig tail.


Thanks again for your help, I actually feel I'm getting somewhere now with this wiring.

nonnieselman

iTrader: (10)

I've never seen a tune from a tahoe.. but on my 2002 PCM with COS3. I can control both my fans with the PCM.

if I was on my laptop I could help you more but it looks like you have everything..

I'm using that same wiring diagram on 3 different trucks and it works great!

Wilde Racing

iTrader: (26)

You will need a resistor to make two speeds with only one fan. unless the fan has a second set of windings....
How many wires are coming out of the fan?

Yes the pcm will control ONE pin outlet (not sure about efi users). I've heard rumors of others getting more than one pin outlet to control fans, but I have never seen hard evidence...

7845

iTrader: (1)

i believe the diagram thta i posted allows the fans to run at low speed by only supplying 6 volts. when 12volts applied they run high speed. but honestly on low youll never have heating issues

Wilde Racing

iTrader: (26)

Where is one going to get 6 volts?
I say, just wire the one pin you can control with hptuners to rune one relay and be done with it. You could get technical and throw another relay in for th a/c clutch... this is of course asuming your fan has only one set of windings.

ces63ss

sorry for the thread hijack but will this wirring diagram work on my 04 sss? I have a set of 05 fans and need to wire them up and have my pcm tuned for them.

thank you, cesar

7845

iTrader: (1)

yes that last diagram i posted will work. its bascially the Nelson harness

InchUp

iTrader: (2)

Ya know guys I really don't know, I'm no electrician. I can build suspensions, motors, car audio systems and I'm still learning how to tune but electrical workings elude me. I've been trying to sit down and figure this out for awhile now but no one really has a direct answer.

Here's what I have:
-Lincoln Mark VIII fan, 3 wires from the harness red, black and yellow all the same gauge (10 or 12 gauge by the looks of it). I have hooked the wires directly up to a car battery to test the fan but I can't remember which wire actually turned the fan on, red or yellow, when I had black grounded. I want to say red and black, but then what's yellow for?

Here is the relay I got to control the fan.






Using some combination of the PCM's tune (I'm 100% ok with just one fan being controlled by the PCM, my custom wiring harness made provisions for "Fan 1 and Fan 2 though...which confuses me) and the relay I have to somehow control the 18" fan. I know from the company who made my harness that the fans are always supplied with 12v, and that the PCM sends a signal to ground fans using the PCM to trigger the relay which completes the ground circuit for the fan, thus turning it on. I was just going to run it on or off, no in between. Now that there's a possibility to have 2 speeds, I'd like to look into that more.

The 18" fan does not have to come on when the A/C is on, I actually see no reason for it unless you guys think so. The 18" fan only cools the radiator which is in my core support. My A/C condenser is remote, stuffed behind the driver side headlight with it's own 8" fan that I was originally going to try to control with the PCM but I'll just piggy back a relay off the A/C request wire off the compressor...no problems I'll take care of it. Right now I'm more interested in the 18" radiator fan.

Here's what really confuses me, from another thread:
https://www.performancetrucks.net/fo...d.php?t=422554

If there's any confusion, I hope this helps separate the 2 fans I have.