PWM cooling fan(s) control using ECM

[erick_e]

Originally Posted by parsonsj

Do those vehicles use PWM fans? My GMPP E67 pn sources back to an 07 Hummer. Anybody know if 07 Hummers have PWM fan control?

2007 H2 and H3 have a fan clutch, so no electric fan.

[4wheels]

The H3 might be an E67 ECM but the 2007 H2 is an E38 and had a conventional mechanical fan (with a thermostatic clutch).

The H3 might have a PWM controlled clutch fan like the Trailblazer etc but it doesn't have a PWM speed controlled electric fan.

Originally Posted by erick_e

2007 H2 and H3 have a fan clutch, so no electric fan.

[4wheels]

Full speed over-ride input for AC, manual fan switch etc but not enough inputs on this controller to accept an AC pressure signal and a temperature sensor. Maybe the next version. 8-)

Originally Posted by parsonsj

Yes, it would be awesome for such a standalone controller to also support an AC pressure sensor. All the fan controllers I've seen just turn on the fans to a set speed (usually 100%) with a 12V input signal when the AC is turned on.

[mikels]

E40, E38 and E67 have ability to control PWM fan or dual discrete or ECM controlled engine driven fan output. All use AC pressure, oil temp, IAT, trans temp as well as coolant to control fan output. Can not mix and match fan driver type - must pick one.

Difference between discrete and PWM is you only have on or off with discrete - which is set to 50% and 100% output from fan cal. PWM drives the motor at whatever the percentage is based on the inputs.

If using the discrete outputs with dual electric, I prefer to set them as parallel / series control rather than have each fan driven by output. That way on 50%, you are driving both fans @ 50% rather than one @ 100%.

I hate listening to noisy fan(s) masking sound of engine - exception being when in track usage - where you NEED the fan output.

Dave

BTW - reason E40 & E67 were used in TBSS and H3 is vehicle communication was still Class 2 while Powertrain was CAN - E40 & E67 can handle both (E38 is CAN only).

[4wheels]

I too prefer to use the three relay parallel/series control on two fans (where both fans are run together low speed or high speed but never individually) but you need to be careful what fans you use for this. Some fan motors don't work well at half voltage (get close to or drop below motor stall speed/torque). Also some fans won't be fuse protected in that configuration (you can stop the blade and fail the motor without blowing the fuse). If you are going to run the series/parallel configuration the easiest is to just use fans that are run that way from the factory (plenty of GM examples to choose from between Camaros, Corvettes, CK trucks etc.).

BTW - if you are running one fan you can also have two speeds with most GM PCM,s/ECMs using a two speed fan relay. Volvo has one that takes two inputs and switches a single fan from low to high speed.

Volvo Cooling Fan 2 Speed Relay, Volvo OE part numbers (used in lots of Volvos so cheap at the junk yard):

• 9442933
• 1398845
• 3523872

Kaehler also manufactures a part that is similiar to the Volvo Cooling Fan Relay. The part number is:

• KAE 3702300

Originally Posted by mikels

.....

If using the discrete outputs with dual electric, I prefer to set them as parallel / series control rather than have each fan driven by output. That way on 50%, you are driving both fans @ 50% rather than one @ 100%.

I hate listening to noisy fan(s) masking sound of engine - exception being when in track usage - where you NEED the fan output.

Dave

BTW - reason E40 & E67 were used in TBSS and H3 is vehicle communication was still Class 2 while Powertrain was CAN - E40 & E67 can handle both (E38 is CAN only).

[parsonsj]

Originally Posted by Dave

exception being when in track usage - where you NEED the fan output.

I'm always battling heat in my '07 Z06 (E38), especially when I run at Sebring. Oil temps often go north of 280*. I'm assuming that my fans aren't running above 35 mph. True? Can that be changed with HPTuners? I gotta admit I've never looked at that...

[mikels]

Originally Posted by parsonsj

I'm always battling heat in my '07 Z06 (E38), especially when I run at Sebring. Oil temps often go north of 280*. I'm assuming that my fans aren't running above 35 mph. True? Can that be changed with HPTuners? I gotta admit I've never looked at that...

There is no speed dependency for fan control. Strictly based on temps vs. fan output %. ECT, EOT, TOT, IAT each have their own table - and highest request wins. What this means is say each input below with respective fan %:
ECT = 60%
EOT = 40%
TOT = 35%
IAT = 0%

Result will be fans driven at 60%.

You can access fan tables with HPT or EFILive.

Don't make mistake in assuming max fan % is only ~90% - so you should raise to 100%. PWM fan controllers have max output at some level <100% (depending on controller). Raising will NOT increase fan output, but can damage fan controller.

BTW- 280 is well within temp limits of synthetic oil, so will present no problems.

Dave

[samckitt]

If you decide to run the Corvette fan module & control the fan from the ECM, I have the module connectors. $55 shipped.

[4wheels]

Dave,

Might not be speed based fan control in the E38 or E67 (I haven't looked at all the code or all the OS's that exist for all of those ECM's to be able to make an across the board statement like that, one way or the other) but plenty of other earlier GM systems did have speed based control criteria. The controllers used with the Gen III GM V8 engines ("Warren PCMs") all had speed based fan control criteria available in the code and most of the vehicles had it enabled.

PSS

Originally Posted by mikels

There is no speed dependency for fan control. Strictly based on temps vs. fan output %. ECT, EOT, TOT, IAT each have their own table - and highest request wins. What this means is say each input below with respective fan %:
ECT = 60%
EOT = 40%
TOT = 35%
IAT = 0%

Result will be fans driven at 60%.

You can access fan tables with HPT or EFILive.

Don't make mistake in assuming max fan % is only ~90% - so you should raise to 100%. PWM fan controllers have max output at some level <100% (depending on controller). Raising will NOT increase fan output, but can damage fan controller.

BTW- 280 is well within temp limits of synthetic oil, so will present no problems.

Dave

[4wheels]

Originally Posted by mikels

...
Don't make mistake in assuming max fan % is only ~90% - so you should raise to 100%. PWM fan controllers have max output at some level <100% (depending on controller). Raising will NOT increase fan output, but can damage fan controller.
...
Dave

Yes, most of the PWM fans reserve the low end of the scale and the high end of the scale for error criteria or other operating modes so most of the fan motor controllers built into the fans are expecting somewhere in the 10% to 20% as initial on speed and somewhere between 80%-90% duty cycle for maximum fan speed control. Above what ever the maximum expected duty cycle won't result in higher speed.

Not saying people should raise the PWM duty cycle over what ever setting than fan is expecting to see but how would this damage the controller? It wouldn't cause it to operate at higher current. The PWM duty cycle doesn't directly control fan speed - it is a fan speed request signal to the internal BLDC motor controller inside the fan. Also the PWM signal is just a communications level signal - it isn't driving any current into the system itself.

Just wondering.