I did ask about the codes the first time it went in, and there were perhaps 11 faults reported that they checked. This led to replacing that switch. On the most recent visit, they reported NO faults, despite the intermittant presence of the lights (it's wierd, some days nothing, the next day on from the start). I'll try speaking with the mechanic who did the work (rather than the manager).
Hope you all get thru the storms OK; Atlanta looks ugly.