I have a CAT CT660S. I have an active code of 3490-3. It is saying the after treatment purge valve is shorted to power. The coil on the purge valve seems to be getting powered all of the time. However I have checked resistance and continuity on the coil wires all the way back to the ACM and everything seems to be checking out. The ACM powers the purge valve, so I am unsure on what direction to head next. Anyone out there have this problem before?
Maxxforce 13 AFT Purge Air Valve
Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by jwills088, Jan 18, 2020.