Always on exhaust brake?

[Midwesterner]

I have been noticing what seems to be the exhaust brake whenever I am slowing down from over 20mph, even when my switch and dash say it is off. Has anyone else noticed this, or am I imagining things? It seems to shut off under 20 mph, as the full exhaust brake does.

 

[AH64ID]

Watch your retarding horsepower gauge to see if it’s activating.

 

[Midwesterner]

It's not showing that it is. To somewhat test, I coasted down a long low hill, from 35. Between 35 and 25 I was decelerating noticeably (1mph every 2-3 seconds), once I got under 25 it began accelerating at a similar rate-all while showing nothing on the gauge

 

[H3LZSN1P3R]

It's not showing that it is. To somewhat test, I coasted down a long low hill, from 35. Between 35 and 25 I was decelerating noticeably (1mph every 2-3 seconds), once I got under 25 it began accelerating at a similar rate-all while showing nothing on the gauge

Thats grade braking in the trans most likely

 

[tchur1]

Thats grade braking in the trans most likely

My thoughts as well. My truck pretty aggressively grade brakes, especially when im unloaded.

OP can you hear the exhaust brake engaging?

 

[Midwesterner]

My thoughts as well. My truck pretty aggressively grade brakes, especially when im unloaded.

OP can you hear the exhaust brake engaging?

I can't hear it engaging distinctly. What is grade braking?

 

[AH64ID]

What makes you think it’s engaging if you can’t hear it?

 

[tchur1]

I can't hear it engaging distinctly. What is grade braking?

If you cant hear it I doubt thats what is causing you to slow.

Grade braking is basically the trans using its gears + engine speed to slow the truck naturally. These trucks are very purpose built to tow so lower gears will work to slow the truck when descending naturally. When I am driving around unloaded I usually have to accelerate a bit to maintain speed when going down grades.

 

[H3LZSN1P3R]

I can't hear it engaging distinctly. What is grade braking?

Its the truck downshifting to slow you down its like downshifting in a manual trans.

 

[Roper46]

My 3500 has been doing this exact same thing and I couldn't figure out what was going on. Thanks for the explanation.

 

[Midwesterner]

If you cant hear it I doubt thats what is causing you to slow.

Grade braking is basically the trans using its gears + engine speed to slow the truck naturally. These trucks are very purpose built to tow so lower gears will work to slow the truck when descending naturally. When I am driving around unloaded I usually have to accelerate a bit to maintain speed when going down grades.

That makes sense. Thanks for the explanation.

 

[techman]

Agree with the others, it is the trans doing its thing. The last thing you want is for the truck to free coast down a incline. With the weight of these things, you would be going Mach 1 pretty quickly without the truck using the trans to keep things in check.

The exhaust brake is a whole other process that is user selected to help maintain speed (auto mode) or aggressively slow the truck (full mode) in all incline/decelerating scenarios.