t800 Jake Brake Problems

I have a 2006 Kenworth t800 Heavy Wrecker with a c15 CAT we just picked up and the jakes are not working at all. When you flip the switch the retarder light comes on and the switch has power but the jakes do not work at all on any stage. Pulled the valve cover and inspected the harness and no chafes or broken/unattached wires. Checked the relay and its working. When hooked up to a Texa Laptop under parameters it shows engine retarder-disabled but doesn't give a way to enable it. Under all the retarder settings there is a Retarder-off/low/medium/high switch setting but the value shows J1/P1:23 & 40 and I can not figure out what this means. Any help would be appreciated. Thanks