Light in instrument panel

Hiya all.... please help.
In the speedo there are lots of lights. I have no manual.
When i go through a puddle...or its really wet outside, i get a slight glow on a lamp...i dontknow what it is.
Its red, next to the 10MPH area, it would be the last lamp on the line. Its somethin to do with brakes....it goues out when i brake or its dry...everything works...nothing makes noises. Strange it flickers sometimes...really softly....i dont think i would see it n daylight, only at night its so soft.
Anyone have a look in the book for me?
mal