PWM cooling fan(s) control using ECM

[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.

[andrewb70]

Originally Posted by samckitt

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

Hey Scot,

Have you actually tried plugging that connector body into a C6 fan controller?

Also, the small terminal that you sent me is not the one that you have in the picture above.

Andrew

[samckitt]

Originally Posted by andrewb70

Hey Scot,

Have you actually tried plugging that connector body into a C6 fan controller?

Also, the small terminal that you sent me is not the one that you have in the picture above.

Andrew

I have one on the Monte. And have sold close to a dozen, no one has mentioned any problem. What problem are you having? All the parts I have for these I keep in the same box, no other parts, so I don't see any way I could have mixed them up. Send me a pic of the small terminal you have.


Scot

[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.

[4wheels]

As Dave pointed out, 280 degrees F is perfectly fine for good synthetic oil. You should be able to run over 300 with good oil (not saying you want it that hot but that it isn't that uncommon). High temperatures will cause some break-down of the oil and additive package so you should change the oil more frequently when it gets that hot. That shouldn't be an issue as I would assume most heavily tracked cars change the oil after each event weekend (and take an oil sample from time to time and send it to Blackstone or some other oil analysis company).

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...