Before I'd spend $1,000 on "tracing" the problem I'd throw some parts at it first in this instance.

I'd start with the brake switch mounted at the top of the pedal arm and then try a K40 relay if that didn't help.

Together they are ~$100 and both are very easy to install.

__________________
Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)