Good afternoon,
After my MOT my rear fog light had rusted through and stopped working, and I ordered a replacement unit. I’ve been all over Google, looked through my Haynes Manual and taken a look these forums, but I’m not having much luck in regards to finding out how to replace it. All I do find is how to fit fog lights to the front of an Mx5 or how to replace a reversing light to a fog light, which isn’t what I’m hoping to do. It’s hard enough finding a guide let alone one with images. I’m pretty new to things like this.
(what my light looks like on the inside)
I’ve been under the car and I’ve been working on removing the rusted nuts and so I’m letting them soak in WD40 for a while.
My main question is this; Is the socket to the side of the left rear light assembly (shown below) the connection to the rear fog lamp?
I can’t trace the wire through the underside of my car. If it isn’t, where is it?
Much obliged
-Glenn 
Hi Glenn
Hopefully your rear foglight is as simple as the one on my 1997 MK1.
The two wire lead runs from a white connector on the left hand side of the inside of the boot near the rear n/s light. You will need to raise the flap of material and hardboard that covers the jack to see it. Simply goes outside the car through a grommit and follows the inside of the bumper skin, held with clips to the fog light.
Ideally your new foglight would have a long enough lead and correct clip to plug and play but if not you will have to cut the existing wiring at a convenient place, preferably in the boot, solder wires together, heatshrink and tape up.