What is this light and why is it on!!!!

Hi, I currently work for a small company out of Chicago OTR. The owner is very poor at maintenance, I have been having this light pop up along with the check engine light and I don't know what it means. It seems to be more common when I have a heavy load, when it is on I cannot use cruise control. To make it go off usually I have to turn off the power switch and sit for 15 min or so but that doesn't always work. The boss always says it's nothing, well it's obviously something! I have a Freightliner cascadia evolution 2014 with 323,000 miles and it is an automatic. The light looks like a truck climbing a hill circled with a line through it exactly like the HSA OVRD switch picture but I push it and it doesn't take the light off. Any help is appreciated!

 

By heavy I mean a load of 40,000lbs or more. It comes on when I turn the truck on after I shut it off. So I leave the truck running constantly whenever I am loaded heavy because otherwise when I start it the light will be on and the cruise won't work. The over ride switch does not make it go off. I am trying to figure out why it comes one when I start my truck and doesn't go off causing my cruise not to work. Other guys in the company don't have this issue with the same truck.