Hope this helps someone with similar problem... Problem fixed by installing Low Pass filters. From Jaycar. See video below. It was most likely RF noise on the line from the alternator. https://www.jaycar.com.au/response-1...ilter/p/AA3074 https://youtu.be/FpyRZhRn02A?si=C5ebiFTsW-AS7GDv Cheers Tony