I feel very, very dumb right now.

So, after roughly 4.5 years without an exhaust brake, I had given up on having one.

I got my hands on my very own Autel Maxisys Ultra from a mechanic friend of mine when he upgraded.

I was playing around in it on my truck and stumbled on an option in the PCM labeled exhaust brake.

Wouldn’t you know it was disabled?

I hit enable and took it off down the road, and it works now.

So, to anyone with this issue, make sure it is on, or you might pull your hair out trying to troubleshoot something you’ll never find.