I need help for a 2000 ML320 that I own I am not sure both theseproblemsare related

Problem : 1 ) When I turn my headlights on the dash goes black (meaning the lights on the dash goes out) I switchheadlights off the dashboard lightscomes back on. I checked all fuses and none of them seem to be out

Problem : 2 ) The Inspection stations (I went to 2 places)are not able to connect to OBD the display says something like "Error unable to establish connection" however when I took it to a mechanic he was able to connect to it and actually showed me an error code which is causing the check engine light to come on need to change the Air mass flow sensor.

Iwill greatly appreciate your kind help

Thank you

 

On problem 1, turn on lights then turn the multifunction switch on the instrument panel. This switch has a dimming function when the light switch ison.