I've got a 1996 300tdi Discovery, the glow plugs won't work (No power) when the yellow/ black cable from the timer is connected. If i disconnect the lead from number 4 glow plug and test it with a meter there is power when the ignition is switched on until the timer switches itself off. I'm thinking it could be an earthing problem from the engine to the chassis, how many earth points are on the engine? And has anyone had the same problem. Cheers Mark