2006 kenworth t800. have no brake lights to truck or trailer.

hey guys. i have a 2006 kenworth t800. we have no brake lights in the truck or in the trailer, we have replaced the air brake switch and tested wiring from rear skirt upto cab. checked all known fuses in truck, tried new relay. when checking relay i noticed all the other light relays have power on 2 of the 5 points of contact but the trailer stop lamp relay only has power to 1 point. if i jump power from #30 plug on relay to # 86 point on relay brake lights turn on. have tried jumping wires to brake switch and completly bypassing the brake switch and still no solution. is there a hidden fuse or secondary brake switch of some sort that im overlooking? havent found any broken wires and am now at a complete loss, any help would be great

 

As far as I can find there are 5 different air switches in the dash and have found 2 on the firewall that all appear to test fine. At a total loss