After suffering with this problem and doing all the usual fixes but nothing seems to really be a good fix , the merc bulb holder fix gave me an idea so here's what I did.

remove your bulb holders and carefully remove the pins and solder wires to them and refit you should end with holders looking like this in picture 1 , then you'll need a pair of rear lights to remove the metal tracks from picture 3 ,you need to leave the tracks in your original lights as this is what keeps the holders in , trim these tracks down so you end up with a pair of sockets like in picture 4 , remove the pins and put a bend in them as per picture 5 , i also trimmed the sockets down as can be seen in picture 6 , then solder the wires to the pins i refitted the holders in the lights to get an idea of wire length make sure you observe how pins where connected in the light as the pre face lift has 5 pins and facelift 4 pins , wrap with some loom tape little bit of epoxy glue to keep the pins in and they you go some plug in looms and bye bye tail light issues , only thing to check is you get all the earths on the holders correct when you put the holders back in your lights.

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