electrical mystery

helppppppppppp my L reg 200tdi disco has developed a mystery fault I will be driving along & suddenly lose side & head lights & hazard warning lights but stop lights & indicaters still work if i switch off engine it will not crank over on key then suddenly all is well its driving me ******* CRAZY

One (or some) of the fusible links in the right hand side of the engine compartment to the rear of the battery has a dry joint.
These links connect the battery to the fusebox.
They are covered in braiding, cut this back and you will see the fusible links, resolder the joints and all should be well.
John

thanks john spot on mate had to go to work on sunday night so got a sparky to sort it out he has replaced all of them cost me £25 next time il know il get some spare just in case many thanks john for going to the trouble of posting a reply