Well that was a thought that I had too. The proximity of the speedo’s internal bulb (that is connected to the lighting circuit) with respect to the speedo’s internal sensitive electronics maybe the noise pathway, so powering the DRL’s from a separate switched supply ‘might’ solve it. It would be easy to check out.
Long term damage….? If it’s just radiated noise I don’t think so but the experts here may have a different opinion?
