I never got that MKIII to work. Once you get the "white screen of death" that's about it. I bought another MKIII locally that I was able to test in my car and it worked fine for about three months before it went dead with the same blank white screen. My alternator went out about a week later so perhaps there were some voltage fluctuations occurring that fried it. My recommendation would be to either move up to a MKIV or down to a MKII (plus the MKII Trimble unit) as the MKIII is just too temperamental.