Controlling LS2 Cooling Fans

[ODeer]

I am new to all this so if I’ve planted a boot in my mouth please forgive me.
Engine LS2 with E40 ECU. Transplanted from 2005 GTO. Cooling fans in original car were controlled by the ECU in two modes via 3 relays. The primary request ran both fans in series at low speed and then the secondary request ran both in parallel at high speed.

EFILive however provides for a graduated output from ECU against coolant temperature. My brain cell cannot see how a graduated demand can be made through the ECU primary/secondary signals to relays. I expected that there would be the same style of control as for LS1 i.e. Fan 1 turn on temp, Fan 2 turn on temp and Off temp.

Can anyone shed light on this please?

Thank you
Terry

[Taz]

Hello Terry,

I am the self professed Gen III guy - have only done a small number of Gen IV conversions at this point in time - so the following is what I believe to be true with respect to PWM fan control. Fan 1 and Fan 2 turn "on" temperatures and turn "off" temperatures are determine by the percentage value entered in the applicable table(s).

The attached PDF file is an example of this process, in an E38 ECM with the EFILive cooling fan patch (extended temperature range) applied to the table values. The table numbers and appearance may be slightly different with your E40 ECM (I don't work with these controllers) but the concept applies.

Hope this helps ...


Regards,
Taz

[ODeer]

Hello Taz

Thank you for an informative reply. That is the most sense I have seen so far on this topic. My brain cell is still at a loss to understand it completely though.

It seems to be much more complex than it need be. Fan switch On I can follow in the examples where a range is given. Switch Off is not so clear. In the text you give values of 49 and 24% respectively for Fan 2 and Fan 1 off. In the table for the LH example the values are 23 and 47%.

Is it that the quoted Off values or lower figures are valid? If that is so my brain cell can have a lie down.

For interest the attachment is the parameters for the E40. To clarify, AC is not used.

Thank you

Terry


12126

[Taz]

... switch Off is not so clear ... is it that the quoted Off values or lower figures are valid? ...

Hello Terry,

You've got it right ... quoted values or lower turn off ... quoted values or higher turn on - each fan (1 or 2) respectively.


Regards,
Taz

[ODeer]

Hello Taz

You are a star. Thanks for that, I'll give it a whirl. I still wonder why we don't have simple settings for each fan on and off. No doubt there will be some electrickery reasoning behind the current (unintentional pun) system.

Thank you

Regards

Terry

[joecar]

The higher-on/lower-off values provide "hysteresis", this prevents the circuit from rapidly cycling on/off/on/off when the temperature is right on the boundary (if there were a single value).

[joecar]

So, the Discrete Fans setting means "series/parallel"...?

[Taz]

So, the Discrete Fans setting means "series/parallel"...?

Hi Joecar ... yes sir. My understanding is the "Discrete" fan setting is for use with relays - like the OEM 3 relay setup used in trucks. Corvette tunes use the "PWM Electric" setting - for use with a fan control module.


Regards,
Taz

[ODeer]

Good Afternoon Taz

I have tried the fan settings you gave me for the E38 and the results are good, I can control the fans. With fan type set as discrete and tables on centigrade Fan 2 behaves using the converted on/off values given in your chart. Fan 1 though will react to 50% as start value as opposed to 25 – 89%. (It might even switch on at a lower value that I haven’t tried.) It turns off at your table value. All temperatures are +/- 1 degree and have been read from Scan/dashboard so should be those that the ECU is seeing.

I’m very pleased to be able to set up the fans in this way. Once again thank you for your assistance and if I experiment and find more information I’ll post it. Next is to find why it idles at 800 rpm even when hot.

Regards
Terry

[LS-SWAPPER]

Old thread, but I need the info. I don't see the pdf file that Taz talks about is post #2. Can anybody give me some info on this? Thanks.

[ODeer]

Hello LS-Sapper,
Try the PDF in post 3 and read it in conjunction with that post and post 9.
It does work.
Terry

[LS-SWAPPER]

Ok, this seems confusing just for the sake of being confusing. I got an engine running on my engine dyno and I think I've figured it out. I set G0927 to discrete like seems to be the going trend, and I was able to turn my 2 fan relays on and off with the scan tool controls. What was really confusing me was what to do with G0901, I couldn't find a solid answer as to what the %s correlated to once the discrete setting was turned on (I understand how it would work with a PWM, but that's not what I'm dealing with on this harness).

Anyway, after getting out a handful of resistors and "creating" different ECT values it appears that anything between 1-49% in the ECT table will trigger fan 1. Anything 51-100% will trigger fan 1 AND fan 2. Honestly, I didn't try 50% exactly, maybe I will do that tomorrow. So here are some screenshots of my settings. Fan one turns on at about 200 degrees then fan2 kicks on ALSO at about 210 deg. The reason I say "about" is because as you see in the 2 dimensional graph as soon as the ramp up % leave the 197 mark it is above 0%. Then with fan 2 the chart gets above 50% right at 209 degrees. I don't see a way to make anymore of a clean on/off setup.

Maybe this was clear to the rest of the members here but it wasn't for me. I've spent weeks reading up and trying to find it written out clearly with no success. Maybe this will help someone down the road. Of course if anyone sees a flaw in what I've just put down, please let me know where I went wrong.

1968319684

[LS-SWAPPER]

Also, I think I know what G0922-0927 are but the descriptions are so confusing that I am second guessing myself. For instance when you click on G0922 the descritpion in the box above reads "Upper limit for High temp Fan after run enable."

...what...???

I'm thinking it could say "Once the ECT reaches this value the fan will continue to run after the ignition is turned off." and make a lot more sense. I've been using EFILive for 4 years now and it is a phenomenally capable tool but it is confusing as H3LL sometimes! It's things like this that have kept me reluctant to learn these Gen4 ecms. I knew it would be a struggle. Ok, rant off.