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I think I figured this debacle out. Since it was a poopie kind of day with down pouring rain, I did some T/S inside. I traced all the wires and figured it out. Relay under kick panel is always powered by key on. One wire goes to solenoids out back. The other wire goes to Jake switch. From Jake switch that wire goes to ECU. I am under the belief that when previous owner had Detroit replace the ECU they (Dealer) did not turn on engine brake feature. I don't think I can turn it on with my DDEC scanner tool. This is my findings.

Hmm I will have to ask my buddy on the WL forum, he has done a deep dive into DDEC, actually so much that he is converting his mechanical 6V into a DDEC IV and he is doing all the programming.