Little Black Box stuck to Class 170 window

[Passenger John]

Was on a GA 3 car 170 dmu today travelling from Norwich to Cambridge in the centre carriage sitting at a table near the middle of the coach. Noticed above me was a little black box stuck to the window and window frame. There was an identical one on the window opposite. Does anyone know what this is for?

 

[Peter Mugridge]

Is it a route indicator for people on the platforms? Most modern units have them.

 

[Crossover]

How little? It sounds like the external side display

 

[SS4]

Was it a perfectly square bit of dirt?

 

[Qwerty133]

How little? It sounds like the external side display

Don't think any 170s have side displays.

 

[asylumxl]

Was it a perfectly square bit of dirt?

Not unless it's Craggy Island .

 

[MCR247]

Don't think any 170s have side displays.

Greater Anglia ones certainly don't, though I have a feeling some of the newer ones (ScotRail?) may have them as I know that 171s have them

 

[Ben.A.98]

Greater Anglia ones certainly don't, though I have a feeling some of the newer ones (ScotRail?) may have them as I know that 171s have them

Pretty sure Scotrail have them.

 

[cuccir]

Have you told the Australians and Chinese?

(bad taste?)

 

[Minilad]

Have you told the Australians and Chinese?

(bad taste?)

Too soon

 

[bronzeonion]

I know exactly what the OP is trying to explain, definitely not a screen.

https://www.flickr.com/photos/34261415@N03/11783770306/in/photostream/

 

[asylumxl]

I know exactly what the OP is trying to explain, definitely not a screen.

https://www.flickr.com/photos/34261415@N03/11783770306/in/photostream/

Do GA 170s have WiFi?

 

[tom1681]

No wi-fi on GA 170s.

I believe it's a sensor for the air conditioning system - to measure sun light coming through the window?

 

[Matt-the-mutt]

If it helps make it a tab bit clearer https://www.flickr.com/photos/dbdi/12705082995

You can not really see it from the outside as i think most of the windows are quite dark when looking from outside to inside. Have to say it would be intrusting to know this!

 

[skyblue]

I think those boxes used to indicate the coach number of the train (A,B or C) when they run down to Liverpool Street but I am unsure as to when they stop using it. My guess would be when they stop the through train down to London.

 

[Passenger John]

Did not notice them from the outside but definitely something electronic, the photos above are correct in what I am taking about.

 

[cjmillsnun]

No wi-fi on GA 170s.

I believe it's a sensor for the air conditioning system - to measure sun light coming through the window?

That makes sense. Certainly climate control systems on cars have similar sensors near the windscreen.

 

[berwicksfinest]

AFAIK they are for display coach letters A, B, C but I haven't seen them working in a fair ew years

 

[shedman]

As others have said they were for coach letters