Earth's...again

I presume it is the earth to the chassis rear crossmember .. I seem to remember it is on the end of the left chassis rail; follow the wires out into the wheel arch behind the left light group and have a look. There are other earths I have found but that is the only one at that end of the car.

if you follow the negative lead from the battery to the bulkhead you will see the cluster of wires that make up the earth circuits....there are braided bonding leads between the engine and the body. others are insulated wires attached to various points like the inner panels of the front wheel arches....under the instrument cluster above the accelerator pedal..most of the back end earthing is fed to this point.... localised corrosion in the rearlight clusters can cause your problem also check the trailer plug..broken wires in the back door interface cable for the wiper and demister are common........

Brown