V70: Electrical intermittent instrument / dash fault

[Phil1116]

All the instruments will flicker or dim, warning lights flash on (inc traction control), and audio sound may cut out momentarily on my 2011 V70. Because this is an intermittent fault it's going to be difficult to come up with a clear fix - at least from a dealer's point of view. The main dealer has run some diagnostics, but not fixed the problem. I suspect a half-hearted attempt by them. My suspicion is a faulty earth or power feed - but I don't have good knowledge of the specifics of the car, but it could be a circuit board failure, or other component. Does anyone have information that I could pass on to them, or to Volvo, to get this sorted out.

Thanks.