Anybody know what this plug is for?

As the title says - does anybody know what this plug is for? Just realised I cannot upload photos for some reason. Anyway, the plug is a 2 pin plug with a yellow and brown wire from it, assume brown is ground. Spade configuration as follows:

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From a 1983 1.8 gti engine, looking at the car, the plug is located just behind the battery and air regulator, almost near the brake servo.  Comes from out of a main wiring loom. I cannot see any obvious places it needs plugging in.

Also, it appears I have something missing. There is a 2 pin sensor and I have 2 of these attached to the brake 'outlets', one immediately out of the servo (that is connected and assume is my brake lights) and this one that is at the end of the manifold, not connected. I cannot see any missing plugs or connections that are obvious. Thanks.

front fogs

end of the manifold one sounds like 5th injector? is it blue?

Thanks rubjonny - thats the reason its unplugged, I have no front fog lights or a switch.

The end of the manifold is just a 2 pin sensor, so its the male end of the spade connector so it has no colours on it. The manifold is the brake manifold.

you mean brake master cylinder? if so its brake light switch, there are 2 of them in a mk1 1 per brake circuit

Yes sorry. That makes sense now. I only have 1 set connected, not two.

Whats the reason for two? And how are they wired? Thanks for the help!

so your brake lights still work if you loos one of your brake circuits. they're wired in parallel, so splice the 2 wires to the 2 wires on the other switch. doesnt even matter which way round you put the wires, its just an open/closed switch

Ah! Thanks, will give that a go!

Hi

Is there a similar one located on the other side of the engine bay near the 5th injector?
It sounds like it could be the spare for side repeaters. Try putting a circuit tester through it and put you indicators on see if it lights up. I know they don't have the side repeaters but mine has a spare connector in that location coming out of the loom for repeaters. It would make any future vw changes easier if the wiring is already in place. That's why they sometimes put extra in.

Hope this helps.