interesting thread this, as my 300tdi has only got one earth cable - and only ever has done as long as I've owned it. There is, and never has been any sign of the one from the starter bolts to the chassis.
Can anyone confirm if this was original to all 300tdi 90s?
Exactly what mine is doing, think its a bad earth on mine - I've always had problems with the earth strap to the chassis.
The other 300tdi in te household barks up straight away despite being left for weeks in the cold. This is also on its original battery as supplied in 1997.