Brake Failure Switch

I found out that My S3 88 has a Brake Failure Switch. It is even connected ! But where should the light be on the dashboard?

A wot? Where?

i fink its on the servo powered split braking system - i think a pressure switch is in the split block if i remember rite.

yep, It's a split breaking system. Under the Servo the 2 lines ( Front- RearBrakes ) comes into the block. On that block there is a switch. If one of the two sides loses presure the switch is activated. But there is no light on my dasboard. I want to put a light somewhere, but I don't know where..

according to my w/s book the warning light for the brake fail switch is on the instrument panel. but the book doesnt show any wiring code easy way to check switch ignition on and this should give you power to the wires join the 2 up and check your dash board,its peeing with rain here so cant go and check on my ser 111,

Is it on a little "v" shaped panel in the middle, alonng with the hazard light switch? (Late Ser IIIs only)

Thanks, I have found an old lamp-socket. That must be it.

can yu test it?

Its on the right hand part of the dash amongst all them silly little toggle switches. Its a red light fitting that pushes in. You can test it by shorting the wires that connect to the balance shuttle valve under the bonnet.
And, as someone pointed out, its one of the [many] s3 features that aint in the Haynes manual.