just stumbled upon your post and the glow plug relay issue. I have a 2010 Grand L3940 Kubota and have a devil of a time starting it in cold weather. You mentioned that you ran a jumper wire from the battery directly to the glow plug connector for 10 seconds. Can you be more specific. Do I simply run a single wire from the positive battery terminal to the connector and hold it there for ten seconds. Then try and start the tractor? Wasn't sure if I needed to have the key switch on while connecting the jumper, etc.. I thought a circuit would need a ground connection as well. Just trying to confirm is this is my problem before pulling the dash, etc.. I've already checked the obvious, fuel filter, battery charged, etc.. thanks.