My girlfiend's TD4 has been sluggish to start for a while now, and now just cranks over. We've replaced the diesel filter, diesel hoses to the injectors in case of air getting in, and latest install is new heater plugs, all without success. We notice the dash has the little orange spring there to indicate that the heater plugs are heating; this is NOT illuminating when the ignition is put on but we're not sure whether it's actually meant to, or ever has actually lit up. My friend thinks there's a problem with the live to the heater plugs; it starts straight away off a tow and diesel is being pumped ok to the injectors. Can anyone shed any light please and also which is the relay for the heater plugs - colour and location PLEASE?? Alternatively - does anyone think it's immobiliser related - is it a common problem? ALL HELP GRATEFULLY APPRECIATED!!!