Hey,
I have a similar problem with my Fiat Bravo 1.4sx!
When I indicate left with headlights turned on, the left brake and tail light flashes alternately instead of the indicator light.
Also, when applying the brake and indicating, I get a constant light in the indicator light instead of flashing..
There are other similar symptoms depending on whether headlights are on or off, and whether the brake is being applied at the same time as indicating left.
No problems when indicating right.
subija, what earthing connection where you thinking about, that could be checked? I'm not sure where to start looking..
Cheers,
Ove