Pacbrake Wiring Diagram. (without) allison transmission (with) abs braking. • oem port pin #9 to on/off switch. CUMMINS ISB/ISC/ISL .Pacbrake Exhaust Brake Wiring Schematic For from fdocuments.in 6 disconnect both negative battery terminals. Web pacbrake exhaust brake wiring schematic cummins isb/isc/isl c/w cm 850 electronic control module on vehicles: (with) allison md3060 wtec iii transmission.