Red lights in Networker.

[theageofthetra]

Sat in carriage 72781 today I noticed two illuminated letters above the luggage rack at the carriage end to the left of the corridor connection. The letter H was not illuminated but the B & C below it were. Any ideas what they are for (am guessing a tell tale for fitters for the heating? )

 

[user15681]

The lights at the carriage ends are to indicate problems. I can't remember what B and C are for, but for example H = heating, T = traction, I = interface monitor. When there's a fault with one of them, the associated light will light up and should in theory stay on until reset. I guess they are there to help the fitters but probably also the driver to identify a fault on his train.