First Post - PWM Fan Control Blue/Red Computer

[snwboarder48]

Hey there guys, just beginning my tuning journey and need a little help. Ive swapped a 5.3 LM4 into a 2004 land rover discovery. BTR truck norris cam. I am using a computer from a 2002 GMC Yukon to control it and I have spent several hours trying to find an answer to this question but have come up blank. Can someone who knows more than I do tell me if this computer is capable of PWM fan control? I would like to take advantage of soft start features and the ability to tune the fans. Can I do an OS upgrade or segment swap to make this happen? Any help would be appreciated. Will probably have many more questions to follow!

Screenshot 2024-09-10 085333.png

[abc]

Post the .HPT file also.

[aknovaman]

i use an Arduino NANO to control Volvo PWM fans. My code generates a 100hz signal to turn on a 19 inch mid-2000's Volvo XC90 PWM fan to high speed (10% duty cycle) when the PCM HIGH speed fan pin is low. Then for low speed, change the pulse width to 90%. Then use another analog input pin to set it to high speed when the AC comresser is commanded ON. Lastly, if the AC is not commanded and the PCM is not commanding a fan to operate, the 100hz output signal is turned OFF. Let me see if I can locate the code at home to share. Granted it's not variable speed, just high and low speed but functional with soft start.

[blindsquirrel]

Can someone who knows more than I do tell me if this computer is capable of PWM fan control?

No. No P01/P59 ever had anything other than relay-controlled fans or a plain thermo clutch mechanical fan. So the PCMs never had any reason to have that ability. The first to have a variable speed fan controlled by the PCM/ECM wasn't until 2005 with the Corvette which was when the E40 appeared.

There are nifty, affordable (i.e. non-Lingenfelter) gadgets that will do it, though with their own controls, not the PCM's. --> https://www.ebay.com/itm/143561646769

[snwboarder48]

Thanks! This is super helpful, all my google-fu wasnt giving me a clear answer. My fan control had the relay control dropdown, but since im new to this whole thing, wasnt sure if there was a software update or anything. Relay control it is!!!!!

[RDF1]

No. No P01/P59 ever had anything other than relay-controlled fans or a plain thermo clutch mechanical fan. So the PCMs never had any reason to have that ability. The first to have a variable speed fan controlled by the PCM/ECM wasn't until 2005 with the Corvette which was when the E40 appeared.

There are nifty, affordable (i.e. non-Lingenfelter) gadgets that will do it, though with their own controls, not the PCM's. --> https://www.ebay.com/itm/143561646769

If you get the BIN for a P59 and use Tuner Pro there are PWM options. Dunno if they work or not tho.

[Fast4.7]

The PWM fan output in the P59 is for the EV Clutch on the Trailblazer.

[blindsquirrel]

The PWM fan output in the P59 is for the EV Clutch on the Trailblazer.

Will it do a frequency that's usable for stuff other than that dumb EV clutch? I know on my E40 with the same fan the PWM EV setting would not put out anything at all at 100 or 125 Hz, but would at the stock 2Hz, confirmed with oscilloscope.

[blindsquirrel]

Oh, nevermind. Frequency isn't adjustable which means it's fixed at 2Hz since the fan hardware is the same for 2002 thru 2009. Not usable for anything other than the stock EV fan.

[Fast4.7]

Will it do a frequency that's usable for stuff other than that dumb EV clutch? I know on my E40 with the same fan the PWM EV setting would not put out anything at all at 100 or 125 Hz, but would at the stock 2Hz, confirmed with oscilloscope.

Never tested it because that EV Clutch is far superior to electric fans for actual cooling. I wanted control over when the clutch engaged especially for ac condenser airflow.

[blindsquirrel]

My SPAL brushless disagrees with that statement.

[Fast4.7]

My SPAL brushless disagrees with that statement.

Your SPAL does not even move half the airflow what my 9-bladed Duramax blade moves through the cooling stack especially with the engine at 2,850 rpm moving 75 mph towing a heavy trailer.

[blindsquirrel]

OK. lol.

[Fast4.7]

OK. lol.

It takes HP to move air. The most powerul brushless Spal I know of is not even 1 hp. The Duramax fan can move 10,000-12,000 cfm through the cooling stack and move airflow even against the backpressure of a super cramped engine compartment.