Thanks for the replies. It's a W Reg mk1 Galaxy, not sure what the engine code is. The main problem is the initial start. Once it's started it will start again without a problem unless it has been left in the cold all day. I've started parking it in the garage, and that has helped a great deal. At least it will start even though it is cranking for a good 20 seconds. After looking at the systems circuit diagrams, I've realised there is not a lot to the glow plug system. I've replaced the glow plugs, so that only leaves the relay, temp semsor or the PCM. I've tried to get to the relay, but its a bit of a mare. I'll try leaving ignition on for ten seconds and see if that helps