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Old 08-03-2022, 04:51 AM   #15
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Originally Posted by DelawareShaw View Post
As for towing with the Tow/Haul mode on, and the exhaust brake(?) on while towing, it is the norm. As far as an exhaust brake goes, only the Cummins has a really good exhaust brake. My old Dodge, God rest its rusted out floors and doors, pulled and did a great job mechanically. The exhaust brake was superior to my GM horses, and low end torque was excellent. The transmission held up equally as well....
I've heard the Dodge has the superior exhaust brake before, but I won't go down that road.

The only other thing I can think of for your GM is it's best to keep the shifter in Drive with the Exhaust Brake set to On if you want the transmission to automatically downshift to help slow you down.

Otherwise, the transmission will not automatically downshift when the Exhaust Brake is On and the shifter is in Manual mode. You can of course manually downshift at that point, though.

The exhaust brake also only activates when the transmission torque converter is locked. I pulled this and above from the diesel supplement manual.

On a related note, I have an Edge Insight monitor (older CTS2 model) and use it to occasionally peek at transmission gear/lock and VGT angle (your issue may be here), among other things such as EGT and engine/trans temp. Highly recommend such a gadget if you like gadgets!
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Old 08-03-2022, 04:53 AM   #16
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As the owner of a 2021 GM 3500 Diesel I speak from my experience. We live in the Sierra Mountains and tow a 5th wheel RV. I speak not as a "flatlander" but someone that lives and drives on steep grades daily. The Duramax Exhaust Brake works well enough that the grade from South Lake Tahoe into Carson City Nevada (Spooner Grade) is a constant steep downgrade with no flat spots. I can set my cruise at 50 mph (towing my 12k fifth wheel) and in tow haul mode, transmission (10 speed) in drive, and exhaust brake on never touch the service brakes except due to traffic or the complete stop at the bottom. I cannot speak for Dodge or Ford but from my experience this exhaust brake meets all my needs with flying colors. We have also towed through Idaho and Montana with similar experiences. If anything, without using cruise control downgrade the exhaust brake may even be too aggressive at times.
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Old 08-04-2022, 06:58 AM   #17
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Mirrors on a 2018 Denali

I wish someone at GM could tell me why an outside door mirror for my 2018 Denali needs to be diesel specific. When you look up the GM part, it states that the mirror for a gas powered truck is not interchangable with a diesel powered truck. Go figure.
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5th wheel, allison, thor

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