Tyer 4506/1 Operation details

[Bernard Grant]

Hi, i need some info, despite searching the web i can find nothing useful about the intended use/operation of this indicator, it has 2 states unlit and lit whereupon the word "OFF" appears in the window, i suspect it is either linked to the sensor in the signal lamp and lights up when the lamp goes out or its to indicate when the arm is in the off position



can anybody shed any light on this, it has the following as part of the rear moulding "Tyer 4506/1" and operates from a 12V DC supply