CM870 Jake Brake Issue

[Psuce1]

I'm putting an updated stock cam in my CM870 and thought I'd see if anyone had any ideas on my Jake issue. When I bought the truck the 3rd stage of the Jake didn't work. I bought the truck that way and also had the truck tuned by a tuner recommended here. It still did not work and he didn't know why it wouldn't work. The truck has the stock VGT turbo on it which is nearly new. I did the turbo test using insite and according to the computer it passed. I could hear the turbo changing pitch and watch the actuator move. I also drove the truck with insite hooked up and according to the computer the engine never demands more than 70% closure of the veins. When I switch the brake switch from stage 2 to stage 3 there is no change in demand for the turbo to close down and obviously no change in the amount the engine holds back. I thought about the Jake switch being bad but when the switch is moved from stage 2 to stage 3 insite shows the Jake going to 100% so the switch is working. Even during normal driving should the engine demand more than 70%? It's like it hits a wall there, it goes to 70 and stops. Has anyone else run into this? Thanks!