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2021 DMAX - cold temp issues?

ArrowsmithPML

By ArrowsmithPML
in 6.6L Duramax Diesel (L5P)

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ArrowsmithPML Enthusiast

ArrowsmithPML

Posted
Posted

So anyone with a 2020 or 2021 dmax that has had any issues with bitter cold winter starts?

Meaning, today it was -50C and trucks would obviously be plugged in. But does a GMC get the DEF tank frozen? 

What about high idles and running / idling for long periods. Any issues?

Colossus Senior Enthusiast

Colossus

Posted
Posted

DEF tank has heaters that will warm up the frozen DEF fluid (and will likely go bad before you hit 100,000 miles, uggh) High idle will kick in (if selected on) after I think.. 20 seconds of normal idle to allow time for oil to circulate thru the engine before putting a slight demand on it.   Plug the truck in for a minimum of 6 hours if temps are what you are describing.  3-4 hours for temps above 0c

ArrowsmithPML Enthusiast

ArrowsmithPML

Posted
  • Author
Posted

Thanks. 

I've got a Cummins RAM and it has proven to less than reliable as of late and it is time for a new truck. So, the 3500 GMC DMAX is the truck. I just wanted to make sure that it would "work" in the bitter cold that we have recently experienced. Yes, that isn't too often and is likely over for the year but...

 

Does the new off the lot truck require a switch to full synthetic 5W40? 

 

Thanks,

redwngr Senior Enthusiast

redwngr

Posted
Posted
On 2/12/2021 at 10:26 AM, ArrowsmithPML said:

Thanks. 

I've got a Cummins RAM and it has proven to less than reliable as of late and it is time for a new truck. So, the 3500 GMC DMAX is the truck. I just wanted to make sure that it would "work" in the bitter cold that we have recently experienced. Yes, that isn't too often and is likely over for the year but...

 

Does the new off the lot truck require a switch to full synthetic 5W40? 

 

Thanks,

Check with the dealer, but I've ran dmaxes and followed several dmax forums for about 15 years and don't recall ever hearing that the factory installs anything other then CJ-4 or CK-4  15W-40. 

 

 

Cut and paste from 2021 6.6L Dmax Supplement:

 

Viscosity Grade 


Use SAE 15W-40 viscosity grade engine oil.  

image.png.4fcc63be11b5a23fbb449bde2dfd2ce2.png

When it is very cold, below −18 °C (0 °F), use
SAE 5W-40 to improve cold starting. These
numbers on the oil container show its
viscosity, or thickness.

 

When selecting an oil of the appropriate
viscosity grade, always select an oil of the
correct specification. See “Specification”
earlier in this section.

 

 

ArrowsmithPML Enthusiast

ArrowsmithPML

Posted
  • Author
Posted

I figured as much so the question is would I be able to get them to do that prior to delivery / ownership? Around these parts stock is very limited and there are no deals to be had due to said shortage. As well has anyone bought the parts from GM Upfitter to do the optional aux switches? None of the dealers around here seem to order as such but these are extremely useful for work trucks.

redwngr Senior Enthusiast

redwngr

Posted
Posted
4 hours ago, ArrowsmithPML said:

I figured as much so the question is would I be able to get them to do that prior to delivery / ownership? Around these parts stock is very limited and there are no deals to be had due to said shortage. As well has anyone bought the parts from GM Upfitter to do the optional aux switches? None of the dealers around here seem to order as such but these are extremely useful for work trucks.

Dealer should do whatever it takes service wise to make the customer happy as far as changing to oil suitable for location/temps of usage.

 

The 'Upfitter' switches can be factory ordered or dealer ordered -- either way there are dealer (at extra cost) installed or customer installed. 

(the factory does NOT install them). 

GM Upfitter website has instructions for install.  Not sure if the instructions are also supplied with the kit.

 

 

ArrowsmithPML Enthusiast

ArrowsmithPML

Posted
  • Author
Posted

I've seen the factory ordered switches on trucks without any dealer input a whopping $175 option. However, in this case, I will be buying all the GM parts from GM and following said directions as it doesn't look all that difficult. 

 

Regardless of who is correct, the point is I need them in there to make the truck work for what I need it to be.

 

Anyway, my old truck is falling apart and isn't worth trading in so I likely just use it as a farm truck or something (not sure). I will have to do something soon though.

 

Thanks for everyone's assistance here though. It has been greatly appreciated.

redwngr Senior Enthusiast

redwngr

Posted
Posted (edited)

If ordering from factory, the current code/description is :

 

 

9L7   Upfitter switch kit, (5), Provides 3-30 amp and 2-20 amp configurable circuits to facilitate installation of aftermarket electrical accessories. Kit with all required parts will be shipped loose with the truck for installation by the dealer or upfitter at customer expense. Installation instructions and technical assistance available at www.gmupfitter.com.

 

Current generation kit is available on all HD trims, and all note about being shipped loose.

 

Previous generation it showed as available on base trims only and there was no note suggesting dealer/customer install required

Edited by redwngr
ArrowsmithPML Enthusiast

ArrowsmithPML

Posted
  • Author
Posted

Fair enough. Funny thing is that they aren't ordered at all down south but are on every truck up north. It doesn't matter really as I need them there so I need to get that done either by them or myself (assuming it is plug and play).

 

By chance do you have any other recommended GMC add-ons that one should consider?

Cheers,

Toddsquad Enthusiast

Toddsquad

Posted
Posted

Ya its plug & play AFTER THE WHOLE DASH & CENTER HAD TO COME OUT OF THE TRUCK TO INSTALL THIS KIT!!! THIS IS SOMETHING THE FACTORY SHOULD BE INSTALLING!!! I'm pretty handy and there is no way I could have done this. And it was not cheap to have installed at my local custom shop. Dealer I bought the truck from had no clue. Dealer one town over has a dedicated guy doing these installs that takes many hours to do the job on my 2021 duramax ltz 3500 

ArrowsmithPML Enthusiast

ArrowsmithPML

Posted
  • Author
Posted
On 2/14/2021 at 12:18 PM, redwngr said:

If ordering from factory, the current code/description is :

 

 

9L7   Upfitter switch kit, (5), Provides 3-30 amp and 2-20 amp configurable circuits to facilitate installation of aftermarket electrical accessories. Kit with all required parts will be shipped loose with the truck for installation by the dealer or upfitter at customer expense. Installation instructions and technical assistance available at www.gmupfitter.com.

 

Current generation kit is available on all HD trims, and all note about being shipped loose.

 

Previous generation it showed as available on base trims only and there was no note suggesting dealer/customer install required

Redwngr,

I bought a new 3500 AT4 - pick it up Friday. No switches. What I found is somewhat disturbing and I thought I would ask you if you knew why - the switches can be ordered but apparently they can't installed as there is a BCM that must be set a certain way at the factory for these to work as intended. That to me seems very odd as to why they are even connected to the computer at all but I don't know enough about it. Short story is that it looks like if I try it without this BCM flashed a particular way, the warranty goes out the window.

 

What I said to the parts manager was that due to my going back to work we would work on this later and he suggested that the knee bolster, the switches / bezel and the wiring harness could be ordered (but not returnable) and I would then be able to wire the end of the harness to power the simple 12V items I want. Seems very logical.

 

Thoughts?

ArrowsmithPML Enthusiast

ArrowsmithPML

Posted
  • Author
Posted

Funny how those very detailed instructions say nothing of the sort. Maybe I'm wrong but it doesn't look all that difficult - time consuming yet but not something that would need programming from the factory. Seems like I was supplied an excuse.

redwngr Senior Enthusiast

redwngr

Posted
Posted (edited)
4 hours ago, ArrowsmithPML said:

Funny how those very detailed instructions say nothing of the sort. Maybe I'm wrong but it doesn't look all that difficult - time consuming yet but not something that would need programming from the factory. Seems like I was supplied an excuse.

I think the parts guy you spoke to is thinking about some other kit....

some addons do require programming updates

 

Edited by redwngr

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