I have a 2001 S80 135,000 miles yesterday the light that lights up the odometer went out,is this a led unit,or a bulb and how do you get to it. all other lights are fine

 

The cluster needs to be pulled out.
Then the bulb can easily be replaced.
There is a couple of screws holding the black part infront of the speedo assembly.
Remove the screws and pull the cover out.
Then there is 4 screws holding the speedo assembly in. Remove them and slide the assembly out and remove the bulb.
it is a regular bulb. Some of them the bulbs are soldered in and others the bulb pulls out.