hi, can anyone help here, have replaced all 4 glow plugs and the relay on our 51 plate 313cdi. glow plug light now comes on with ignition but goes at in about 10secs but the glow plugs have not come on. Glow plug light then comes on for a minute after the van starts. If i disconnect the relay and direct wire the plugs all the glow plugs are working. it looks to me like a faulty brand new relay or have missed something silly?