Ask your buddy at the shop if his scanner will manually turn the valve off and on. If it does make sure you have power and ground to valve, power to valve is constant as long as key is on. Ground is supplied thru ecm as seen fit. The vent control valve is normally open and ecm grounds it/closes to run pressure test on evaporative emmission test to check for leaks. It has a pressure sensor on the charcoal canister that ecm looks at to check for leaks/voltage drop, this sensor is sensitive to dirt and debris. Any kind of restriction in hose going to vent control valve, or canister and the ecm will kick the vent valve code. Priorty 1 is to check for power and ground to valve. 2nd look and check for restrictions in hose or canister.Have him check this and report back to us and I will try to help all I can without having truck to look at. Evaporative emmission codes are tough to diag so be patient.