Hi, my instrument cluster lights do not work. Are there troubleshooting steps or common failures for this?

Thanks.

 

Here's a good start. A lot of very good info here: https://mercedessource.com/store/sea...=Dash%20lights

 

On my w123 coupe I pulled out the instrument cluster and made sure the bulbs worked with a 12v drill battery. For me when that wasn't the issue I started to look at the board itself. I gently took it apart and there were a lot of burnt traces on the board itself. I couldn't do it myself so I took a electrician and he fixed it up for me. but when I plugged it in it still didn't work. I later came to realize that somehow the park lights having bad ground can also prevent them from working.
If I were you with the new found knowledge I have I would do this in order.
Check fuses
Make sure 15pin mushroom is cleaned and seated properly.
Check all grounds. behind cluster, rear right taillights. front right taillights even one under the car near the oil pan. To remove the gauge cluster you need a special tool it looks like a thin long piece of metal with handles on one end and a notch on the other.
Check the bulbs/reflector these can go bad and not cause the lights to work.
Inspect board for burnt traces,
Make sure 15pin mushroom is cleaned and seated properly.

 

Check the rheostat controlling the bulb intensity. They stop working after 40 odd years. You can take it out, or just solder a wire onto the two pins, effectively bypassing it and putting the dash lights in its brightest setting. I replaced the two illumination bulbs with LED's as well.

 

Burnt traces almost always occur due to someone inserting/removing a bulb with the power (lights) on.