2020 3>0 Duramax Exhaust Brake

Powderman9 · March 28, 2020

Picked up mine March 11 so far so good. Getting amazing fuel mileage compared to my '17 5.3. The one issue I'm wondering about is the exhaust brake. I have a long steep hill on my commute. When I switch to tow\haul prior to approaching the hill and touch the brakes as the decent begins, nothing seems to happen. The truck picks up speed rapidly, there is no change to engine/exhaust noise. I had a Duramax 6.6 years ago and it was obvious when the exhaust brake was working regardless of the load in the truck. Has anyone experienced this? Is it normal? Also, I wish GM would have just put a button on the EB like the V8 Duramax.

CamGTP · March 28, 2020

Do you have to ride the brake for a little longer than just a tap to make it engage??

Whipped500 · March 29, 2020

Try cruise control... I don't have mine yet but I thought I remember that was what TFL figured out when testing. It's definitely not like it's big brother though.

redwngr · March 29, 2020

Bonus is that turning tow/hail on also disables the auto stop/start.

From; https://gm-techlink.com/?p=12048

3.0L Diesel Engine

The diesel exhaust brake function on the 3.0L diesel engine is part of the Tow/Haul Mode Grade Braking system. Tow/Haul Mode Grade Braking is only enabled while the Tow/Haul Mode is selected.

On vehicles equipped with Driver Mode Control, Tow/Haul Mode can be activated/deactivated by turning the Driver Mode knob to the left. (Fig. 11) When selected, the Tow/Haul Mode symbol will illuminate in the instrument cluster.

Fig. 11

If the vehicle is turned off with Tow/Haul Mode active for less than four hours, Tow/Haul will remain active after the vehicle has been turned on again. Otherwise, the vehicle will start in Normal Mode.

For vehicles without Driver Mode Control, press the Tow/Haul button on the center of the instrument panel.

TIP: The Automatic Engine Stop/Start system is unavailable when the Tow/Haul Mode is active.

Powderman9 · March 29, 2020

I’ve tried riding the brake as well. The transmission doesn’t downshift either.

MTU Alum · March 29, 2020

The exhaust brake on the 3.0L does not have the authority the 6.6L has. The grade braking in transmission is not as aggressive as the HD. You really need to hit the brakes hard to get it to Downshift. It works a lot different than the HD trucks.

#iworkforGM

Pswa320 · March 30, 2020

cruise control or manually downshift and the exhaust brake is effective. gears 8-10 are all overdrive gears and won't do much. get it into a lower gear.

jbdart66 · April 8, 2021

I have a 2021 AT4 and have the same problem. The 1500 while touted as a great tow vehicle has no electronic or exhaust braking - thus it just rolls very nicely forever and you get to melt your brakes even on flat surfaces. Very disappointed and my dealer has no answers. Oh, they do offer a $3K brake upgrade so you can go about a mile further on a steep mountain decent until they melt. That should help, not.

I called bankspower.com and according the engineer I talked to they have no plans to offer a unit for the 3.0L. From what I can tell there is no brake option for the 1500. Ridiculous. I do understand how to use the manual shifting to lock out upper gears... this has little effect, it just causes higher RPM but little to no braking because a diesel does not have a throttle like a gas engine - just fuel injectors.

steve841 · April 9, 2021

An early review mentioned that the exhaust brake was more show than slow ... I presume due to the smaller engine.

redwngr · April 9, 2021

17 hours ago, jbdart66 said:

I have a 2021 AT4 and have the same problem. The 1500 while touted as a great tow vehicle has no electronic or exhaust braking - thus it just rolls very nicely forever and you get to melt your brakes even on flat surfaces. Very disappointed and my dealer has no answers. Oh, they do offer a $3K brake upgrade so you can go about a mile further on a steep mountain decent until they melt. That should help, not.

I called bankspower.com and according the engineer I talked to they have no plans to offer a unit for the 3.0L. From what I can tell there is no brake option for the 1500. Ridiculous. I do understand how to use the manual shifting to lock out upper gears... this has little effect, it just causes higher RPM but little to no braking because a diesel does not have a throttle like a gas engine - just fuel injectors.

3.0L exhaust brake is only active when the truck is in tow/haul.

newdude · April 9, 2021

1 hour ago, steve841 said:

An early review mentioned that the exhaust brake was more show than slow ... I presume due to the smaller engine.

If its programmed to work like the 2020 HD, its now a more progressive setup. If the truck is loaded up with trailer or weight, it will work more aggressively than if empty.

My 2016 Colorado diesel worked only in tow/haul just like the 1500 but its operation was like the 2011-2019 HD in where you'd feel it more empty than the new trucks. Felt a tiny bit stronger with a trailer but nothing really noticeable.

Edited April 9, 2021 by newdude