Have a look at the Glow Heater Relay unit. On a previous M-Jet Fiat I've had, the bolt that holds the ring terminal for the positive feed to the Heater Relay had rusted away completely. I took the box apart and permanently soldered a length of heavy enough wire to the "Feed In" on the inside of the box. You then seal up the box again and connect your new wires to the car's original cable and re-fit the box.
MJ150 - I still get 'Check glow plugs' error, but I have fitted 4 new plugs and a brand new relay:bang: It's embarassing when u start up in a dense cloud of blue smoke, so what can I check now?