Hi,

My van has a feature which really impressed me when it first automatically kicked in. Grade Braking. I haven't quite experienced it enough to understand exactly how it functions, but if I am on a steep decline and I use the brakes the transmission automatically downshifts using the engine as a brake.

I assume it uses input from an angle sensor, combined with many other factors. It comes on automatically regardless of tow mode. I've left my foot on the brake with reduced pressure thinking I had to, but the last time I took my foot off and it kept engine braking. I actually don't know what I did, but the decline was very long and steep, eventually it even downshifted further and scared the.. out of me because it was whining coming down the hill as if I had a turbocharger.

It's a neat feature to have work automatically, I just wish I knew the details of how it worked without doing laps on long hills to figure it out. Sometimes I would actually like to coast and gain speed, even if it results in speeding far above the speed limit.

 

Its a fine line for the engine brake to kick on. Sometimes Ill be going down a hill and want it to kick on.. and it does not. I believe if you put your foot on the gas it will turn it off. But yes, I have the same questions as you.

 

On our dodge caravan we had it was tied to the cruise control. It would downshift to keep from coasting too far above the set speed.

 

That's certainly not the case here.

 

Okay.
Have you read this?
Grade Braking Operation on Full-size Trucks

 

Well that certainly answers a lot of questions. Good article.


But it is active regardless if cruise is on or not. My van doesn't even have cruise control.

 

I saw that. Its too bad the article does not clearly state how to defeat or turn off the system in all models.
Have you checked with the dealer? Or GM customer service direct. I am glad I don't have this as I like to gear down manually and coast when I need to.

 

I actually don't mind it.. but couldn't make sense as to why it only kicks on when it feels like it. Sometimes it will kick on and surprise you, other times towing a trailer... I kept wanting it to kick on and it wouldn't.


According to the article, all the data has to meet certain parameters. Such as how long your foot is on the brake etc. (and for my year I can turn it off by holding the tow haul button.)


Reading again, my questions are answered. Hope the same for the OP as well.

 

Yes, it did answer a lot of questions. Thank you for posting that.