Hi Robert, the LCD and keypad backlight can be turned on and off using the Auto Backlight (ABR) menu option (Menu 22), however there is no dim feature for it on the KG-UVD1P.
There are a few factors that determine the longevity of any LCD display assembly, including where and how it was stored. The KG-UVD1P is a very reliable and rugged radio, so a failing backlight is not something we generally hear about with this model. In fact, it’s one of our best selling Wouxun radios, and it is rarely returned. We get fewer returns on the KG-UVD1P than almost any other brand of business radio, and it is one of the reasons we worked with Wouxun to base their new KG-805 GMRS and MURS radios on a model platform similar to the KG-UVD1P.
It is not unusual for any LCD Display or backlight to dim over over time as a device ages. Whether it’s a large LCD monitor or a tiny display on a radio, they can fade over a long period of time. I repaired my share of LCD computer monitors and laptop displays over the years, and it was fairly common for the backlight panels to fade or go out, especially in the early days. The backlights on LCD screens of two way radios are not that much different, just smaller.
From what you described, it sounds like the backlight on the display is going out. While it may be possible to replace the backlight, we don’t currently carry the part for it, simply because we seldom get one back from which we could pull the part, and the cost of repair is likely more than what a new unit would cost.