(31 Mar 2017, 7:52 pm)EL1TE wrote I don't think I've ever seen 6139 with a working side or rear destination...Thats because they dont work. 6138 has about 10 seconds off for 5 seconds on. 6129 also resets and the rear display is barely viewable. 5239's rear display also barely spends anytime on. 6038's rear display is also fixed on "0". 3887's rear display does not work. 643 and 645's side displays flash with weird characters on. And many more...
I think we can draw a conclusion that displays, typically displays which are not front displays don't seem to be required to be working. If there is a horribly defective front display, they get pulled off the road - but this is rare.