Adjusting cooling fans to operate at highway speeds if needed?

[[email protected]]

Gentleman,

This is for 09' GMC SIERRA 2500HD with stock E38 computer. It uses factory dual fans setup. Everything is tuned as stock (same as 1500 Series trucks).

These are the only options I got to play with for cooling fans:

1- Fan Desired % vs. AC Pressure
2- Fan Desired % vs. ECT

I have discovered through the scanner that the factory default OFF for the fans is when the speed reaches ~45 mph regardless of the other two parameters, I need to know if I can alter this. If so, please let me know in details and which beta will support this? I think maybe if I update the software/beta other parameters may be visible? If anyone has any experience directly related to this, please let me know. I'm sure others would benefit.

Thanks!

[hjtrbo]

A clear log with the above parameters would be handy.

In your examples does the AC pressure and or the ECT PWM setpoint put into a fan state where at least 1 fan should be commanded on?
If yes, the fans are reporting off in the scanner?
If yes, then you are right and it looks like we are missing another table.

The OS I've seen does not reference speed at all but it does reference EOT and TOT as well as AC and ECT. We don't have those tables mapped either. I have seen another OS where the EOT and TOT tables were zero'd out so not all OS's use them.

[Shrek]

There are many Gen 4 fan modifiers - as hjtrbo has indicated.

With Gen 4 calibrations there are vehicle speed related fan modifiers (often not defined in HPT) that can inhibit fan operation.

Corvette calibrations always have these parameters set to the maximum speed - such that fan operation is never inhibited by vehicle speed.

Gen 4 Truck calibrations may sometimes have nonsensical vehicle speed fan modifier settings. This may sometimes included a short range or "window" where fan operation is inhibited by vehicle speed. The most common "window" inhibits fan operation between vehicle speeds of approximately 50 MPH to 65 MPH.

In your case the lower end of this range seems to be around 45 MPH. If you were to drive the vehicle on a highway, at 70 MPH (or more) - you may find that fan operation is no longer inhibited by vehicle speed.

[[email protected]]

hjtrbo,

In your examples does the AC pressure and or the ECT PWM setpoint put into a fan state where at least 1 fan should be commanded on?
In our trucks, both fans are either on/off in low and high speed. They are relay controlled. The set points for AC and ECT work flawlessly as intended/programmed, but my issue is on speeds above 45 mph where it neglects the previous parameters and shuts the fans off permanently regardless of the set points in (AC pressures and ECT). Unless speed is reduced to ~25 mph, where it will now depend on the AC pressures and ECT so when speed comes into play, everything else is disregarded. This is not very desirable in my opinion, say for example the coolant temperature reaches 220 Fahrenheit, I want the fans to kick in. By the way, I realized that 2007 to 2014 YUKONS/TAHOES E38 ECM is set to work this way from factory, but I wanted to know if they are adjustable somehow but is not showing via HPtuners parameters? EDIT: To share accurate information to fellow HPtuners Members; I've just learned that my above statement/issue apparently involves 2009 through (2013 SIERRAS); (2014 YUKONS/TAHOES). So 2007 and 2008 models in fact do implement the tables I need for the 'Vehicle Speed Adjust' as per Shrek's shared information. C6 Corvettes too implement these fan parameters.

If yes, the fans are reporting off in the scanner?
Oh yes, they are showing their states via the scanner and they are right on; applying the tune.


Shrek,

I have seen the C6 CORVETTES work as you mentioned. I like that, well their fans uses PWM but it doesn't matter. I wish my fans work the same way but in low speed and not shut off early at 45 mph. I'm thinking something like: OK shut off at 45 mph, but if the temperature reaches 215+ then keep the fans running at low speed then shut off at 205 F. and so on.

If you know how I may apply: "vehicle speed fan modifier settings" please let me know.

Thank you both for sharing your thoughts

Bader

[Shrek]

Regarding Gen 4 E38 ECM vehicle speed fan modifiers.

If you look at 2008 E38 OS 12617631 - the above are defined for both Corvette and Truck calibrations.

Go to System > Fans > Vehicle Speed Adjust

Look at:
ECM 8052 - Vehicle Speed Lo
ECM 8053 - Vehicle Speed Hi
ECM 8054 - Vehicle Speed Max

Your 2009 Truck is likely using E38 OS 12630501.

The above described parameters have not been defined by HPT for 2009 E38 OS 12630501. You would need to submit a support ticket, and ask that these parameters be added.

[hjtrbo]

Hi Shrek, would it be possible for you to post both of those OS's? I can get the binaries from those files and should be able to find the addresses if the offsets aren't to far apart. If I can get those addresses to the OP HP support will implement those tables alot faster.

I'm glad you mentioned all this as now I will look for those in my binary and add them to my UDPs. They will come in handy for my interchiller.

[Tfoggy]

I am also interested in this for my 2014 Yukon Denali. E38.. It runs so freakin hot while towing at highway ish speeds around -55-60 mph..
I know for sure the fans are NOT On. If I get into a little town or something and slow down, the fans come on a temp go back to normal.
It concerns me that my ECT's run 220-230 while towing because then my trans temps go up to.. And I have a very large mishimoto all alum radiator..
SO it's not a coolant flow issue at .. Strictly airflow at the speeds 45-65 mph.

[[email protected]]

Regarding Gen 4 E38 ECM vehicle speed fan modifiers.

If you look at 2008 E38 OS 12617631 - the above are defined for both Corvette and Truck calibrations.

Go to System > Fans > Vehicle Speed Adjust

Look at:
ECM 8052 - Vehicle Speed Lo
ECM 8053 - Vehicle Speed Hi
ECM 8054 - Vehicle Speed Max

Your 2009 Truck is likely using E38 OS 12630501.

The above described parameters have not been defined by HPT for 2009 E38 OS 12630501. You would need to submit a support ticket, and ask that these parameters be added.

You got me interested regarding submitting a support ticket to add the specified parameter. Although I have never done this before, is it something that will be available for the public within the next beta update or how does it work? Assuming HPtuners will approve it and work on it. I really don't know how this gets done.

Thanks for your feedback!

Bader

[Sanadatamna]

Is it ok to bump this old thread? I can't find anywhere what does ECM 8052/8053/8054 stand for.

I only want my fans to run by ECT, not by speed or anything else, how can I do this ?
Couldn't find info anywhere