how does the rear foglight work? do i need vagcom or a euro switch?
If you straight swap the lights the rear fog light will come on when you put the car in reverse.
You need to code the car (using vagcom) to stop this happening (details in this thread - eg. byte 18 to 15 if halogen fronts).
Then it doesnt work at all.
It is also a non-removeable LED.
To get use of the rear fog light you have to get a euroswitch and a trigger wire (two of them if you also want to utilise the front parking lights setting).
You need to wire the trigger wires to the black cecem under the dash and do some wiring swaps between the black and brown cecms (details and instructions are elsewhere in the forum).
Then you will be able to use the euro switch to enable the rear to come on when you pull out the switch two notches and you get an orange indication light come on in the instrument cluster.
EDIT:
The rear fog light is a bright red led light - it should be mandatory worldwide! Aids visibility for cars behind to see you better in foggy (and low visibility) conditions.
No soldering required - the trigger wires just click in. Make sure to flip up the clip on the cars headlight switch wiring harness to make it easy to push in the trigger wires.
Getting the wires out of the CECMs are a pain in the ass. Best to use pins into the harness small holes at the bottom to push the wire (and wire pin) out of the harness. And its very awkward working down there. Need to cut some of the wiring black tape back to get room to swap the wires.
The wiring to be done for the rear fog:
I'm sure there are other threads with pictures etc.
Here is a good one
- install trigger wire from euro switch pin #7 to black cecm pin# 17
- move wire from black cecm pin #28 to brown cecm pin #47
- move wire from brown cecm pin #47 to black cecm pin #28
- vagcom coding under 09 central electronics, byte 18, change to either "04" or "21" (for bi-xenon fronts) or "15" (for halogen fronts)
For the front parking lights you need another trigger wire installed from euro switch pin #3 to black cecm pin #19.
Trigger wire (also known as repair wire) part number is 000979009E.
See here for more on installing euroswitch and trigger wires