David, does the check engine light work? If so, does it flicker? I had same model last week, but I had comms whilst check light was working, but it did not work all of the time. The code given when I could make comms was that the ECU had lost it's memory. This was traced to the thinnest of the red wires in the ECU multiplug, connected fused live feed to it and all was well. I think Tony is right and you have a wiring fault, time for pin out testing, Good Luck! Gwyn