PWM cooling fan(s) control using ECM

[parsonsj]

Originally Posted by Dave

This functionality is built into OEM control logic (E40, E38, E67, etc. with PWM fan control.

Except for GMPP controllers. GM deliberately disabled the PWM fan control logic (along with AC pressure sensor input and reverse lockout, and who knows what else) to reduce warranty issues.

[mikels]

Originally Posted by parsonsj

Except for GMPP controllers. GM deliberately disabled the PWM fan control logic (along with AC pressure sensor input and reverse lockout, and who knows what else) to reduce warranty issues.

Not true - it's in there. Main change was to make controller incompatable to use (with GMPP software) in a production vehicle - so you can't defeat theft systems.

Dave

[parsonsj]

Originally Posted by Dave

Not true - it's in there. Main change was to make controller incompatable to use (with GMPP software) in a production vehicle - so you can't defeat theft systems.

I wish you were right!!

I spent a month with a GMPP LS9 (E67) controller trying to get the fans to work. HPTuners happily let me make the changes to the fan tables, but the PWM control wire didn't have a signal. I finally opened a support case with GMPP, and tech support told me that fan control (and AC pressure, and reverse logic, etc.) was deliberately disabled in the GMPP E67s.

I switched to a salvage yard E67 from a V6 Malibu and got that working immediately (wrote ZR1 OS, then copied the GMPP tune plus the fans).

I even documented my journey in this very thread a few pages back.

[samckitt]

I have the GMPP LS2 controller kit and turned on the PWM fan and reverse lockout functionality using HP TUNER. Assuming the AC pressure for fan works too. Haven't teases that yet

[mikels]

Originally Posted by parsonsj

I wish you were right!!

I spent a month with a GMPP LS9 (E67) controller trying to get the fans to work. HPTuners happily let me make the changes to the fan tables, but the PWM control wire didn't have a signal. I finally opened a support case with GMPP, and tech support told me that fan control (and AC pressure, and reverse logic, etc.) was deliberately disabled in the GMPP E67s.

I switched to a salvage yard E67 from a V6 Malibu and got that working immediately (wrote ZR1 OS, then copied the GMPP tune plus the fans).

I even documented my journey in this very thread a few pages back.

May be an issue of HPT not having correct address of fan type selection, but I can assure you - the software is in there.

BTW - GMPP tech support may be technically correct in that it is 'disabled' - but only by bit selection (not removal of code).

Dave

[parsonsj]

Originally Posted by mikels

May be an issue of HPT not having correct address of fan type selection, but I can assure you - the software is in there.

BTW - GMPP tech support may be technically correct in that it is 'disabled' - but only by bit selection (not removal of code).

Dave

I hear ya on the "bit selection". Quite likely in the OS, rather than the hardware/firmware. And not only is the fan disabled, but the AC pressure sensor input is disabled too. I verified both with side by side testing. I was told the reverse lockout was also disabled, but didn't verify with testing.

I was also told that over-writing the GMPP E67 with a later model passenger OS would likely "brick" it. That's why I used a salvage yard 2012 MY controller.

[andrewb70]

Originally Posted by mikels

....

Stand-alone controller would need provisions for a scaled 0-5V input based on AC pressure with a cal relating that pressure to a requested output. And same logic where highest request wins.

Dave

I am pretty sure this can be implemented in the Holley Dominator. Every output can be configured to have multiple trigger events. The Dominator also has quite a bit of programmable inputs.

However, doing all that seems like overkill on my old jalopy...LOL

Andrew

[andrewb70]

Originally Posted by mikels

May be an issue of HPT not having correct address of fan type selection, but I can assure you - the software is in there.

BTW - GMPP tech support may be technically correct in that it is 'disabled' - but only by bit selection (not removal of code).

Dave

Dave,

First of all, thank you for all the information that you have provided. It has been invaluable!

John and I discussed this in detail and we suspect that at some point GMPP altered the E67 ECUs that come with their kits.

Lous69 was able to make it work on his Camaro and so have others I believe. I bought my GMPP kit back in 2008, but I have yet to implement this on my GTO.

As stated earlier, I think at some point GMPP made changes to the ECU, most likely at the OS level. It doesn't seem likely that GM would alter the ECU at the hardware level as that would greatly increase cost. But making simple revisions to the OS probably only required some programming time, which only adds a little bit of cost.

This is all conjecture of course as we don't have the knowledge or the needed software tools to know for sure.

Andrew

[4wheels]

It isn't at the hardware level because that same part number (before it becomes a GMPP ECU) is used in some model year production vehicle applications.

You can also put the GMPP calibration into the production vehicle service part if you get the correct part number ECU. And you can put production software in the GMPP ECU if you make sure it is a compatible OS (careful because if it isn't compatible you can "brick it").

As far as I know only two OS's exist for the GMPP E67 ECU's:
12638778
19211212

Neither of these OS's are used in production vehicle applications.

Anyone know of any other OS's used in the GMPP E67s?

As was already pointed out differences exist in the GMPP calibration compared to the production vehicle calibrations for anti-theft related reasons so that the GMPP ECM can't be used as a way to bypass GM's production anti-theft ECU calibration logic. Plugging a GMPP ECU into a production vehicle can't be used as a way to bypass the anti-theft requirements of the production applications (to meet Federal vehicle anti-theft requirements).

Originally Posted by andrewb70

Dave,

First of all, thank you for all the information that you have provided. It has been invaluable!

John and I discussed this in detail and we suspect that at some point GMPP altered the E67 ECUs that come with their kits.

Lous69 was able to make it work on his Camaro and so have others I believe. I bought my GMPP kit back in 2008, but I have yet to implement this on my GTO.

As stated earlier, I think at some point GMPP made changes to the ECU, most likely at the OS level. It doesn't seem likely that GM would alter the ECU at the hardware level as that would greatly increase cost. But making simple revisions to the OS probably only required some programming time, which only adds a little bit of cost.

This is all conjecture of course as we don't have the knowledge or the needed software tools to know for sure.

Andrew

[parsonsj]

It isn't at the hardware level because that same part number (before it becomes a GMPP ECU) is used in some model year production vehicle applications.

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?