2020 3.0 Diesel Engine fan Racing (Diesel particulate filter?)

Truckasaurus · January 14, 2020

I have a month-old 3.0L Duramax AT4 and this morning (temps in the low 30s), the electric radiator fan came on full speed while i was warming up the truck. It remained on throughout my commute, and came immediately back on when i fired the truck up 6 hours later to leave. I've read that the Diesel Particulate Filter (DPF) requires occasional flushing at elevated temperature and the manual indicates that the exhaust and such runs hot during this process so that the engine fan may be increased during this time. However, i also read that there would be some sort of notice on the dash about this mode being on and I received no such notice. I just rolled over 1100 miles.

Can anyone with one of these new DuraMaxe owners confirm that this is what's going on, or is there something else going on here? I can't find reference to anything related to DPF cleaning or purging anywhere in the infotainment or dash menus,,, It's pretty annoying because it's 32 degrees out, the water temp gage is so low as to not even appear (i.e., below 160) and the damn fan is running like i just drove 100 mph in arizona in the summer for an hour.

becker87 · January 14, 2020

I have close to 6000 miles on mine. The trucks to go through a Regen mode so clean out the DPF. I have never seen a light on the dash telling me it is doing a cycle. I have driven the truck normal when I think it is running and have turned it off with no issue.

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Booger T · January 14, 2020

I've only noticed one regen with mine and I probably wouldn't have noticed it but I had to stop for some road construction and had window down and I could smell it, never seen any dash light telling me it was doing it. That was around 350 -400 miles, have just shy of 800 on it now and have not noticed it since. As far as fan running and coolant temp being low I never noticed anything out of the ordinary.

Truckasaurus · January 14, 2020

I have "smelled" the regen cycles in the past, but this thing with the electric cooling fan maxed out when it's 32 degrees out is bizzarre. Now i'm starting to worry that it's something broken.

Chrisd534 · January 14, 2020

1 hour ago, Truckasaurus said:

I have "smelled" the regen cycles in the past, but this thing with the electric cooling fan maxed out when it's 32 degrees out is bizzarre. Now i'm starting to worry that it's something broken.

https://gm-techlink.com/?p=12389

Truckasaurus · January 14, 2020

22 minutes ago, Chrisd534 said:

https://gm-techlink.com/?p=12389

This! Exactly what must have happened. I used the block heater last night and it didn’t get a full six hours of cold soak yet. Thanks!

Colossus · January 14, 2020

From that link: "Also inform the customer to avoid engine block heater use in temperatures above 0°F/–18°C. While the owner’s manual states an engine block heater should be used in temperatures less than 0°F/–18°C, it isn’t vital until much lower temperatures of less than –13°F/–25°C."

My big boy durmax sure starts a lot easier and warms up faster when I have the block heater running for a minimum of 2 hours every morning prior to start in the wintertime.

Klientook · October 24, 2020

Does anyone know if there has been a fix to this issue?

Brandonb0013 · February 8, 2021

On 10/24/2020 at 12:55 PM, Klientook said:

Does anyone know if there has been a fix to this issue?

So it has finally gotten cold enough here in WI to test this out. This weekend I plugged in the block heater and started the vehicle when it was below 0F, but the fans still kicked on. The ambient air temp of the truck claimed it was 10F, but that was obviously wrong. It's possible that is why the fans kicked on. Regardless, I am going to call the dealership today to find out the status of an update. Hard to believe that there wouldn't be a fix for this when there are articles online dating back to 2019... I'll post back with an update later today.

redwngr · February 8, 2021

On 1/13/2020 at 9:08 PM, Truckasaurus said:

I have a month-old 3.0L Duramax AT4 and this morning (temps in the low 30s), the electric radiator fan came on full speed while i was warming up the truck. It remained on throughout my commute, and came immediately back on when i fired the truck up 6 hours later to leave. I've read that the Diesel Particulate Filter (DPF) requires occasional flushing at elevated temperature and the manual indicates that the exhaust and such runs hot during this process so that the engine fan may be increased during this time. However, i also read that there would be some sort of notice on the dash about this mode being on and I received no such notice. I just rolled over 1100 miles.

Can anyone with one of these new DuraMaxe owners confirm that this is what's going on, or is there something else going on here? I can't find reference to anything related to DPF cleaning or purging anywhere in the infotainment or dash menus,,, It's pretty annoying because it's 32 degrees out, the water temp gage is so low as to not even appear (i.e., below 160) and the damn fan is running like i just drove 100 mph in arizona in the summer for an hour.

The techlink article has already been posted -- and it's possible that the programming solution is now available.

FWIW.

Finally got some colder weather 'here'. We've had lots in the upper teens. but last night it was low single digits by 11pm.

It had climbed to about 8F by the time I decided to see how it would start this am without the block heater - - and as expected (based on years of starting the 6.6L diesel in similar temps, without use of the block heater) it fired right up with none of the hesitation or rough running that older diesels had a reputation for having.

Round about way of saying that in the low 30's you won't need the block heater for a dmax.

Truckasaurus · February 8, 2021

50 minutes ago, redwngr said:

The techlink article has already been posted -- and it's possible that the programming solution is now available.

FWIW.

Finally got some colder weather 'here'. We've had lots in the upper teens. but last night it was low single digits by 11pm.

It had climbed to about 8F by the time I decided to see how it would start this am without the block heater - - and as expected (based on years of starting the 6.6L diesel in similar temps, without use of the block heater) it fired right up with none of the hesitation or rough running that older diesels had a reputation for having.

Round about way of saying that in the low 30's you won't need the block heater for a dmax.

Thanks, This was corrected with a software update some time ago, so it's not really an issue any longer. My primary motivation for going with the block heater wasn't for cold start, so much as it was so that i could have HEAT a lot faster upon cold start.... having the heated block yields a heated cabin a lot faster.

Turns out it was a software glitch that if the block heater was used in temperatures greater than some threshhold, the computer would think the engine was overheating and go into full fan mode... and was only defeatable by turning off the truck for 30 minutes to reset.

Klientook · February 8, 2021

Truckasaurus

When was this corrected? Do you any further info?

I have had this problem and my dealer says this has not been addressed. Last time I plugged in 10 below and the fans went full blast 1 month ago.

GMC Ryan · February 8, 2021

6 hours ago, Brandonb0013 said:

So it has finally gotten cold enough here in WI to test this out. This weekend I plugged in the block heater and started the vehicle when it was below 0F, but the fans still kicked on. The ambient air temp of the truck claimed it was 10F, but that was obviously wrong. It's possible that is why the fans kicked on. Regardless, I am going to call the dealership today to find out the status of an update. Hard to believe that there wouldn't be a fix for this when there are articles online dating back to 2019... I'll post back with an update later today.

I'm curious to hear what you find out. My truck was built in January 2020 and not sure if I have the latest ECM programming the Techlink article mentions. Thanks for digging!

Klientook · February 8, 2021

GMC Ryan

Where does it say that there is updated programming in the tech link article?

Brandonb0013 · February 8, 2021

Dropped it off at the dealership this evening. They said there was no service bulletin for this issue and they were not aware of it. I printed off this article and left it with them since it explains it better than I can. I will have more information tomorrow. I am not aware when my truck was manufactured, but it is a 2020 model.