Can I not run dual SPAL fans independently with an E67 PCM?

[LJS3SP]

GM PN# 19354333
--This is the PCM for an LS376/525.

SPAL fans PN# - 30102022


I have re-rerouted the blue trigger wire of the (blue + green) ganged pair from under the GM harness's (PN 19166573) fan relay to a separate fan relay which is the chassis' native fan relay.

So I use the GM harness to power on the primary fan, and the native chassis harness (non-GM) to power the secondary fan.

Calibration file is untouched except for MAF and Speedo calibration.

At 203F both fans turn on, and stay on until the car turns off.
Now the fact that both fans turn on indicates to me that this particular harness has two trigger wires for the GM fan relay that are being controlled by a single driver in the PCM. Is this correct?

What I don't understand is why both fans are not shutting off or is there no threshold in this PCM's stock calibration file to do so?

[blindsquirrel]

Funny how much easier it would be to answer this if it were possible to see the settings in your tune file. If only there were a 'Manage attachments' button you could click...

[LJS3SP]

My bad....attached

[pannetron]

The ECU has controls for two fans. As far as I know, once the ECU turns the fans on, it won't turn them off while the vehicle is at a standstill. Check under System/Fans and make sure the number of fans is set to two. Then set the Relay Controls as you like. I use this kit -- https://www.pcmofnc.com/product-cate...ing-system-19/ -- and like it. The additional relays mount in the GM harness fuse box. It runs the fans in series at first for less noise then in parallel at full speed at the upper temperature threshold.

[blindsquirrel]

State vs Desired is way wrong, all 100's for every cell. Output Control vs State is also I think wrong for what you are wanting, that one has both ECM pins doing the same thing at the same time, and not staged or independent when set like that.

[LJS3SP]

Ok...this is starting to make some sense now.

The SPAL fans are identical, and are not brushless.
Driver(primary) / passenger(secondary) side pulling air through the heat exchangers.

So I have three desired states triggered by temperature:
1- both OFF
2- Primary ON secondary OFF
3- Primary ON secondary ON

I'm guessing the "state" of 0 thru 7 is temperature increments.
output cont v curr state.PNG
"1" up in the header row is apparently 203F as that is currently when both fans turn on. Where can I find the corresponding temps for 2 - 7?


Am I correct that the transition desired vs current state table only applies to PWM fans? Or does it need the two ON states populated into it accordingly?
state trans des v curr state.PNG

I'm obviously not thinking about this in the same way as the software is set up because the desired fan % vs ECT table has more than 8 (0 thru 7) increments.
des fan vs ECT.PNG

So how do I set the secondary fan to turn on at 225F?
And how do I see when each fan turns off as ECT declines?

[blindsquirrel]

How are your fans wired? I know the way you explained it makes sense to you, but not necessarily to anybody else who has never seen your wiring and so has no picture of it in their head.

Is it just both fans on at full speed, or both fans off, both doing the same thing at the same time? Or are they series-wired for low speed, and parallel-wired for high speed (three relay)? Or completely independent?

(and no, none of those guesses are correct about how the tables relate to each other)

[LJS3SP]

Looks like this:
diagram.PNG

The primary fan is just wired directly from the provided power wire in the GM harness and grounded to the chassis.

[Alvin]

The ECU has controls for two fans. As far as I know, once the ECU turns the fans on, it won't turn them off while the vehicle is at a standstill. Check under System/Fans and make sure the number of fans is set to two. Then set the Relay Controls as you like. I use this kit -- https://www.pcmofnc.com/product-cate...ing-system-19/ -- and like it. The additional relays mount in the GM harness fuse box. It runs the fans in series at first for less noise then in parallel at full speed at the upper temperature threshold.

Thanks for the recommendation..
Here is a link to the GMPP kit.. Its nice cause it reuses the factory fuse block, you add a fuse, a new relay.. move a couple pins around and you have high speed and low speed control.
https://www.pcmofnc.com/product/gmpp...ric-fan-kit-3/

You are aware that the factory GMPP wiring ties both high and low signals together? They are spliced together at the fuse block.



I also got a A/C fan speed bump circuit.. What it does is mix AC control into the fans.. If the fans are off and AC comes on..they go to low. If already at low.. they go to high.


This should get you fans working assuming they are wired right.

LS376_525_ECU_Base_03 FANS.hpt

[LJS3SP]

Is it just both fans on at full speed, or both fans off, both doing the same thing at the same time? Or are they series-wired for low speed, and parallel-wired for high speed (three relay)? Or completely independent?

Right now...both fans turn on at 203F and stay on. They are single speed fans as far as I know, that's why I posted the SPAL PN...in case I am mistaken and someone here has used these fans differently.
The car is in the break-in period, so I cannot say if the fans are turning off while in motion as I have not logged any of the break-in drives. Fans came on and ECTs dropped when idling so I called it good for getting the first oil interval done and decided to figure out the discrepancy between how the fans *should* work vs how they *are* working, later.

It is now "later".

[LJS3SP]

This should get you fans working assuming they are wired right.

LS376_525_ECU_Base_03 FANS.hpt

The secondary fan is wired according to the diagram posted, not shown in the diagram is the Primary fan which is directly off the GM harness and grounded to chassis.

Thanks for the file. I'll take a look and ask if I don't understand something...which is likely.

[LJS3SP]

You are aware that the factory GMPP wiring ties both high and low signals together? They are spliced together at the fuse block.
LS376_525_ECU_Base_03 FANS.hpt

Maybe...
If you are referring to the ganged pair of blue + green trigger wires under the single GM fan relay...then yes, I re-routed the blue trigger wire according to the diagram

[gtstorey]

Ok...this is starting to make some sense now.

The SPAL fans are identical, and are not brushless.
Driver(primary) / passenger(secondary) side pulling air through the heat exchangers.

So I have three desired states triggered by temperature:
1- both OFF
2- Primary ON secondary OFF
3- Primary ON secondary ON

I'm guessing the "state" of 0 thru 7 is temperature increments.
output cont v curr state.PNG
"1" up in the header row is apparently 203F as that is currently when both fans turn on. Where can I find the corresponding temps for 2 - 7?


Am I correct that the transition desired vs current state table only applies to PWM fans? Or does it need the two ON states populated into it accordingly?
state trans des v curr state.PNG

I'm obviously not thinking about this in the same way as the software is set up because the desired fan % vs ECT table has more than 8 (0 thru 7) increments.
des fan vs ECT.PNG

So how do I set the secondary fan to turn on at 225F?
And how do I see when each fan turns off as ECT declines?

I think the way this works is ECM sees a temperature and looks at table 18030. It compares that temp to the desired fan percent. It takes that percent to table 18040 to look up a desired fan transition of state. It then takes that state transition to table 18045 to decide which fan is turned on.

Yours doesn't change state until it hits 203 and you call for 100%. 100% is all transition states. And all but state 0 is both fans running. When the temp falls to 199.4 the ecm calls for 0% but you don't have a transition state for 0% in table 18040 so it has no way to go to state 0 to turn off the fans. What I'm not sure about is how it handles duplication of percentages in 18040. But if you put 0% in the lower half of 18040 it should allow the fans to cut off. You can also set some in between percentages in 18030 and 18040. Try setting 18030 at 199.4 to 50% and 203 to 100%. Set 18040 0>1 to 50%, 1>2 through 6>7 to 100% and 1>0 to 0%, 2>1 to 50% and the rest to 100%. Table 18045 Column 0 to 0,0,0 Column 1 to 1,0,0 Column 2-7 to 1,1,0.

You should get 1 fan on at about 199.4, 2 fans around 203, back to 1 fan at 199.4 and off below 199.4 (these temps may not be exact since it probably interpolates between the temps). This is assuming you have the wiring to support what these tables are trying to do.

[LJS3SP]

Ok gents I appreciate the replies and the file.
My remaining question is:

Is "fan %" a speed value? Meaning 100% is full speed, and 50% is half speed, etc?
I was under the impression that these SPAL fans with brush motors only had 1 speed, ON...is this not the case?

[gtstorey]

Computer doesn't know what fan is attached. My response is for the ECM that is controlling discreet (not PWM) fans. Is there a setting in this ECM for Discreet or PWM?

[LJS3SP]

Computer doesn't know what fan is attached. My response is for the ECM that is controlling discreet (not PWM) fans. Is there a setting in this ECM for Discreet or PWM?

Yes, it is set to discrete.
Again these fans are NOT brushless.
This has been explained to me that it means these fans are not variable speed fans.

I will use Alvin's values he shared with me but I am asking the dumb questions first....like "Can these desired fan %'s be used with a non-brushless fan?"

I know nothing about electric fans. I am trying to ensure I don't make or project incorrect presumptions that end up forcing me to replace brand new hardware.

[gtstorey]

I missed seeing that Alvin had posted a correct tune.

The actual percentage doesn’t mean anything, it just values that are used to look up a change in state in another table. I’m pretty sure you could put 0% in as full speed and 100% in as off, when it discreet mode and make it work.

Your fans currently work, you just don’t have the settings set up right to turn them off.

[blindsquirrel]

If you want a system where you just type in the temperature where the fans turn on, you should have bought a Holley. All this unnecessary complication is not something HP Tuners invented just to make you miserable, they are just giving you a tool to see what is in the GM ECM and it works the way GM designed it. You're wanting the stock ECM to be user-friendly and dumbed-down like it was aftermarket EFI. It is not that. I am sorry.

[LJS3SP]

If you want a system where you just type in the temperature where the fans turn on, you should have bought a Holley. All this unnecessary complication is not something HP Tuners invented just to make you miserable, they are just giving you a tool to see what is in the GM ECM and it works the way GM designed it. You're wanting the stock ECM to be user-friendly and dumbed-down like it was aftermarket EFI. It is not that. I am sorry.

I am asking pretty relevant questions. Other GM and Mopar PCMs actually have these tables set up in quite intuitive ways and are HPTuners-supported.
However, I'm sure Holley appreciates the plug from a class act like yourself.

Perhaps I should just trial and error until the table functions become apparent to me? Sounds like the absolute stupidest thing to do if countless others have already walked this path and a simple explanation...which apparently you do not possess or are too much of a crank to share...is only a question away.


Since you clearly have nothing to contribute, how about you sit on your hands, maybe go for a walk and get some fresh air, and let those who actually have something to contribute, do so, rather than clogging up the thread.

Thanks.
You are dismissed and ignored.

[LJS3SP]

I missed seeing that Alvin had posted a correct tune.

The actual percentage doesn’t mean anything, it just values that are used to look up a change in state in another table. I’m pretty sure you could put 0% in as full speed and 100% in as off, when it discreet mode and make it work.

Your fans currently work, you just don’t have the settings set up right to turn them off.

No problem.

That was the root of my entire misunderstanding of what was going on in these tables.
I actually came across this revelation last night when I found a video where Alvin or a colleague explains this. Video link posted below for future reference
http:https://youtu.be/862kJez6su4?si...F9ROEd&t=262//
Info pertaining to my confusion in this thread starts around 4:24


Once I understood that these values are arbitrary for a "discrete" setup such as mine, I went ahead and copied Alvin's values over and the car runs with fan function precisely as intended. The only task that remains is to do some logging on the road and see if any tweaking is even necessary.

Thanks to both of you for your help and explanation to clear things up for me.