I have a Snap-on Mt 2500, with VCI 5.2, I am having a comm. error issue on a 2004 Ford F-550 with the 6.0L. I am using the CAN 1b adapter and key 17 as instructed. I have tried both VIN specific and Global OBD, using key 20 for global obd, with no success. I t... Login to read more.