Wheel lock light

Exactly what the title says I notice there is a wheel lock light on my 88 ram 50 4x4 and every d50 I have had made past 87 has one.. what is it for? I notice I have 2 sets of wires coming off the t case.. there is one set of wires I know is for the 4x4 dash light and then another that comes off the rear of the t case on the opposite side of where the front drive line is.. is it to tell you your auto front hubs are engaged or if you had manual that they needed to be engaged?

Is one not a backup light switch also? They all look the same to me!

Well yes haha but that comes out of the tranny lol I'm talking about the t case lol