Frank Erskine wrote:
On Sun, 2 Jan 2011 14:40:01 -0800 (PST), Andy Dingley
wrote:

On Jan 2, 9:02 pm, Roger Mills wrote:

As others have said, it's pretty certainly an earthing fault.

You can diagnose rear light cluster earthing faults quite easily -
look for a Ford or Renault badge. However they make them, they
haven't got reliable earths to the rear clusters.

It would probably be much better to use a wire "earth" return, rather
than rely on the chassis.

No experience with the Kagoo but I presume that the rear light cluster has a
'buzz bar' type of common earth that could suffer from corrosion, there
could be a problem with the wire connection to this, a problem where one
filament on a twin filament bulb has failed (usually the lower wattage one)
allowing a leakeage to earth across the indicator light etc, could be
problem
with loose bulb or even a poor connection to the live or earth bulb
connections etc etc.

A *competent* DiYer usually finds the more persistent fault[s] by simply
taking the cluster off and:

1 Check the incoming cables at the connector for power etc with a
multimeter and clean off and remake the chassis earthpoint (with a French
car, that could be halfway down the body of the car and in the most
inaccessible of places [at least that was the situation on the wife's
Citroen when the bloody headlight/side light cluster started playing up a
few years ago]).

2 And if the above fails, take the rear cluster into a nice warm
workshop, remove and check all
the bulbs, then connect the cluster to a battery charger (or even a spare
battery) and methodically work through every electrical trail using a
multimeter or simply a good bulb with a couple of tails soldered onto it
until the problem is found - usually around 15 minutes to check and resolve
the problem.