where which earth's ?

[franx]

I know there is one at the alternator, one at the battery (-terminal connected to chassis). Any more ?

Car has developed a misfire/judder and a diagnosis/readout brought up a faultcode mentioning bad earth ... ?

 

[SkidMarx]

Theres no earth on the alternator.

Theres one bolted to the gearbox casing, diff area.