Wotz this do?

[Michael.McD]

Apart from switching the red led above it on and off?

[Plotloss]

Central Locking?

Just a guess...

[judas]

Wing mirror heater/demister?

[sacha]

if you have it, it is for the wing mirror de icer's

[cacatous]

Yep! Demists the mirrors. Well that's that sorted!