NAV screen is dim now no matter what I do
 

Hi,
The NAV screen on my '05 4.4 sports has gone dim for the second time now and no matter what I do this time around, it hasn't gone back to the usual brightness it has had. The first time it dimmed (about a month ago) I drove the car hard and it brightened up next time the car was started- it may have been a fluke. Now I've done the same, updated the NAV OS to the latest (v32), ensured the brightness settings are on the highest level, the instrument cluster dimmer knob is on brightest setting - all to avail. The color scheme is on 1 but even on 2 it's still dim.
I was suspecting the battery (still original) but no starting problems or other lighting problems so I figured it can't be the battery. Is there a bulb in there that may need to be replaced? Has anyone experienced such a weird issue?
05 X5 4.4 sports 62K miles.:dunno:

The LCD backlight will be failling.

In some countries you can demand replacement under guarranty, as your car is only 5 yrs old. Depends on what consumer protection laws you have in your country.

Read your guarranty carefully and then talk to your BMW dealer in your country.

Had the battery checked out multiple times and no problems with it. In any case, now NAV screen is bright blue like it used to be (as opposed to yellowish dim as before). The temp in Northwest went up and car has been driven more in the last 3 weeks or so. It appears to be the battery but don't know what exactly what. Never ahppened in the past. Battery is original (2005).

A replacement battery is cheap compared to a replacement screen

So throw a new battery in and monitor the situation

However, my bet is screen or poor connections to screen...

I concur with Jochen, LCD backlight.