91 Explorer Low Range 4x4 LED Remains Illuminated

[Dancing Bear]

1991 Explorer, and the low range 4x4 LED sometimes remains illuminated. 4x4 functions perfectly, engages and disengages as it should, and the low range also appears to function as it should. I have heard this illuminated LED may be a code for a problem with the 4x4 system, but since mine seems to be functioning correctly, I was wondering if there is a sensor that I should take a look at that may be causing this.

Thanks in advance for any input!