Am after some information from others with the C9 engine brake. At times it appears not to work, but perhaps I don't understand how it supposed to work. There are times that I flip the switch and nothing appears to be happening, and nothing shows on the Allison panel to show that it has engaged. Is there a speed limitation at which it will turn on/engage that I am not aware of? My understanding that this is a CAT product right? Do I have a problem that I need to have CAT address? Other times it acts like I would expect, I flip the switch and it engages. Anybody know what is happening?