23 Trail Boss w/3.0L Duramax Exhaust Brake

Haufski762 · March 3

Gents, How does this work? When I hit the tow haul mode it notifies me the exhaust brake is active but I don't hear it or feel it. I am unloaded but driving down steep grades and trying to use it to help slow me down so I don't have to ride the brakes as much.

Am I missing something?

Jay P · March 3

Not missing anything. It's only a 3.0l engine so it doesn't do much especially if you compare it to the 6.6l diesel exhaust brake.

Jay

Haufski762 · March 4

I can't imagine I wouldn't feel anything.

I watched a video on YT and the guy said you have to apply steady pedal pressure to get the brake to activate. His RPMS kept jumping up the longer he held down the pedal.

He was pulling a trailer when he was filming. I also recall applying steady pedal pressure but never got the RPM increase. I wonder if it only activates if you have a trailer.

redwngr · March 5

It's kinda like glorified powertrain grade braking.

It's definitely has a less aggressive 'feel' than the exhaust brake on the LML ('11) and L5P ('18) 6.6's that had previously.

Of course the loads it's intended to hold/slow are also much lower than what the 6.6's are expected to manage.

With cruise set the exhaust brake and powertrain grade braking will work to hold the speed from increasing above the set speed. Truck will also downshift as necessary to increase the braking provided.