Rear light wiring the plugs have numbers on them 1-6 here are the colours for each pin.
O/S
1 BLACK/RED
2GREY/RED
3 NOT IN USE
4 BROWN
5 BLACK/GREEN
6 GREY/WHITE
N/S
1BLUE/BACK
2WHITE?BLACK
3BROWN
4NOT IN USE
5RED/BLACK
6BLACK/GREY
If you blow your car up its not my fault this is only a
GUIDE
Some comments based on experience changing my Mark I lights to Mark II last month:
You need a Torx T20 bit to remove the light assemblies. There is a single screw for each assembly next to the tailgate opening. They originally came with a black plastic cover but these usually get discarded at some point in the car's life.
When the screw is out, gently move the light assembly horizontally towards the outside of the car. Two pins on the light assembly will disengage from two rubber grommets in metal tabs that are welded to the car body. Sometimes a grommet will come out - make sure you don't lose it, and make sure the grommet is fully home in the metal tab before you refit the light assembly.
You then need to remove the six pin plug that connects the wiring loom to the light assembly. There are securing clips at each end of the plug that need to be eased out. The plug has a flap that opens, revealing the contacts and numbers 1 to 6 which are referred to in the list quoted above.
To re-arrange the wires you need to remove most of the contacts from the plastic six pin plug. I found this very fiddly and opted to buy new plugs from the local dealer - in this case VW. The part number is 893 971 636. They cost less than £1 each. I carefully cut off the old plugs with side cutters, taking care not to damage the original contacts.
However, I later found that the contacts were easily removed using a paper clip.
The 'new' offside lights worked first time but I had a
problem with the nearside lights. The reversing light didn't work. I also had problems with my auto gearbox - I could only get reverse and third gears to work.
The
problem was that the wiring new offside light unit did not need the blue/black wire from the wiring loom, so I thought I would put it in the "not in use" socket (No.4). What I hadn't realised was that this No.4 contact was connected to No.3, which is earth. The black/blue wire is the live supply for the reversing light, so whenever the gear selector was in reverse, this caused a direct short to earth and blew the fuse. The fuse supplies the reversing light and the auto gearbox ECU, hence the problems with only one forward gear.
The remedy was to remove the blue/black wire from the six pin plug and tape it up. With a new fuse fitted, the single (nearside) reversing light worked and so did the gearbox. Job done!