adamscamaro

I have a 1967 Camaro RS/SS with a 2005 GTO LS2 installed and it has been running great for over 2+ years. I just recently installed a new LSX style aluminum dual pass radiator with 2 electric fans on it. My last radiator/fan setup I had a switch that I would just toggle on and off as needed. This new fan setup comes with the necessary relays, wiring & a 180 NPT sensor that is supposed to control when the fans come on and off. With that said, the LS2 engine has 1 port in the driver side of the head which is used by the computer and the other one I was using for my electrical temp gauge. Now I have the 180 NPT sensor and no where to install it. I tried making a T piping out of NPT which I believe will do the trick.
I was wondering, since the computer is already using one of the ports for the temperature, is there any way to tap into the computer or wiring and have it turn on and off these fans some how?
I have been searching on the internet for a while for some answers and haven't found anything concrete. Any help, guidance or suggestions would be greatly appreciated. Thanks in advance.

rotor vs. piston

iTrader: (3)

The computer itself can control the fan relays. I wish I didn't eliminate this from my computer as I now have an extra box doing this.

If you have a programmer or a know someone that does they can set your on/off temps. The only issue I can see you having is that you already cut the wires from your PCM or at least they're wrapped somewhere in your loom.

adamscamaro

My question is which wires do I need to run to my fans to get them to power on and in what order. I believe there is pin 36 from the ECM which is the low power fan and pin 56 which is the high power fan. If I'm not mistaken the fans are turned on by grounding them with either wire. At least I believe that is how they work. I have everything wired for my fans to function like that and right now the way they ground is by the 180 NPT sensor. Once the sensor heats up to 180 degrees it sends a ground signal to each of the fans to complete the circuit and then they kick on via the relays and power wires.
What I need to know is how do I get the ECM to perform this function instead of the 180 NPT sensor.
Do I hook both the 36 pin (Low) & the 56 pin (high) fan wires to my two fan ground leads? Or do I hook the 36 pin to one of the fan ground leads and the other 56 pin to the other fan ground lead?
Has anyone done this and if so what was the process?
Thanks for the response.

rotor vs. piston

iTrader: (3)

If your PCM still has the function it should control the ground to the fan relay, not the fan itself. If you have access to the wire check for a closed circuit when your engine heats up, use your volt meter and have your positive lead on the + of the battery and your negative on the wire coming from those pins. If you have voltage when the engine heats up then your PCM can still control your relays.

adamscamaro

So was what I stated correct? Pin 36 is for the Low fan relay and Pin 56 is for the High fan relay? Then you take Pin 36 and wire it to one of the fan ground wires and then take Pin 56 and run it to the other fan ground wire?
So the low fan pin 36 will only trigger one fan to come on at a lower setting and when the engine gets even hotter the high fan pin 56 will trigger the second fan to come on?
What are the stock parameters because I haven't done anything to them and I'm wondering if what is stated above is done if it will be adequate to keep the engine cool as is.
It can't be that easy could it? Pin 36 to one fan ground wire and Pin 56 to the other fan ground wire?

adamscamaro

Yeah sorry for the confusion. My new fan setup has 2 relays and the ground wires going to the fan relays are what are grounded by the 180 NPT sensor. Once it heats up to 180 degrees it grounds those two wires that run back to the relays and then in turn completes the circuit or sends the signal for the fans to kick on.
So I need to get access to the PCM, locate the two pins (36 & 56), get my volt meter out, touch my + lead to the battery and the negative to either pin once the engine heats up and if I have voltage I can run my two ground wires running from my two fan relays which are currently running to the 180 NPT sensor to either of those two pins?
Does that sound like what I need to do?
Thanks for your help guys.

rotor vs. piston

iTrader: (3)

Yep, sounds exactly right.

Anyone, please correct me if I'm overlooking something.

adamscamaro

Well I will give it a try and see where I get. At least I have some where to begin. Thanks

TomM

iTrader: (56)

It's that easy, however, after looking at a 2005 GTO tune file, I don't see where there is an option to set second fan temperature, that's why I deleted my post, so I could check for sure.

Are you running the 05 ECM or something else......if not what ECM/year model are you running?

T,

adamscamaro

I am running the 2005 GTO PCM/ECM that came with the engine and the original wire harness. I have the pinout and it says that 36 is for the low fan and 56 is for the high fan.

Blue67LS2

iTrader: (2)

Did you ever come up with a solution? I have a similar issue I'm trying to figure out and would appreciate any info...

Thanks!

adamscamaro

I actually never got it wired with the ecm. I ended up just using the supplied thermostat & wiring kit which came with the radiator I purchased.

jimmyjam

iTrader: (1)

Just want to share some info and maybe someone who knows better can correct me if I’m wrong.

I've got dual spal fans in my tbss now that are just on/off now and i want to run them hi/lo. The tbss comes with a clutch fan controlled by a single wire (pin 36 pin), so I’ve got to add a pin to 56 in the harness for hi speed.

Three relays are needed for hi/lo speed on dual fans. The first relay is attached to pin 36. The other two are attached to pin 56 and switch the fans from being wired in series (lo) vs parallel (hi). I'm also going to put an 2sec RC delay on the hi relays to force a "soft start" in the event the ecm commands them to go from off to hi (these fans draw 37A a piece momentarily spinning up @ full speed)

From there you can use HPTuners to modify how they work. For example, my 06 tbss uses the same ecm as an 06 gto so i looked at their tables. The ECT and AC pressure tables are controlled by "desired fan %". Values 0-49 are off, 50-89 are lo speed, 90-100 are hi speed. The effect of these % values is determined by "Fan output control vs current state" and "Fan State transition desired % vs Current state" tables.

Waiting on some 40a relays to come in before implementing this. If I’ve gotten something wrong, please enlighten me.