threadlight

My CLK280 has been having an issue where the dash shuts off, and then all the dash lights come on over the span of 2-3 seconds. This happens completely randomly both during startup and while driving, and affects the car differently in each case.

If it happens while trying to start:
- Causes issues with starting, either the car would not crank at all and take a few turns of the key, or it will crank for less than a second and then stop at the same time as the dash turning off
- It seems to happen more often during cold starts after the car has been sitting overnight

If it happens while driving:
- If the car is travelling at a decent speed it always recovers by itself, as if nothing has happened
- If the car is stopped or moving slowly the engine will cut out, but always started right back up after putting it in park

Some extra notes
- Every time this happens the radio and interior lights stay on and dont dim, but the dash and other lights on the center console (parktronic, passenger airbag light etc) turn off and back on.
- One time, after driving for just 5 minutes the dash turned off and came on rapidly about 4-5 times as if there was a loose connection somewhere, but was fine for the rest of the day
- Issue has slowly started becoming more and more frequent over the course of 2-3 months
- Happens with both keys
- No check engine light or OBD codes

The battery and terminal connections were checked by a mechanic and were all good but he could not find the cause of the problem, the diagnostic scan showed that the rear SAM, EIS, and steering column came up with undervoltage faults, along with a few others that don't seem to be related






Any help on where/what to start checking from here would be greatly appreciated, thanks