Very happy with my 3597, but struck a problem yesterday which through a spanner in the works. Driving in full daylight, the screen was set to high brightness and Display Timeout to 'Never'. But the brightness would keep returning to 20% which was near impossible to see in the sunlight. After resetting and confirming brightness to even 100%, it would still return to 20% after a minute or two.
Then the complete reverse problem when driving later that night. The brightness kept jumping up to 100% which was very distracting in the dark.
Went back and checked that there wasn't a hidden menu I'd missed in the instructions and couldn't find any mention of this problem in this forum so did the obligatory Google and found references to needing to set the Current Time to 'Automatic'. It appears that unless this is checked, the unit gets confused and doesn't know if it is meant to be day or night.
Have done a couple of short tests and this appears to have resolved my problem. Although with the explanation, I understand the association (of time and automatic dimming), I would never have found this setting without others having shared the resolution.
Thanks for the tip - the same thing happened in my Garmin Nuvi 2598. I have done as you suggested and changed the time to automatic and, hey presto, it seems to do the trick. It's about time that Garmin provided a handbook with all these details!!
Many thanks for posting this! My first Garmin GPS, 2 days usage, and thought it was a lemon!! The automatic setting makes sense but do wonder why Garmin have not made this a default setting. Thanks again!! :
The answer that keeps on giving!! Having put up with the screen dimming while driving in the UK (with minor annoyance) it became truly unbearable while on holiday in the US. It seems to work.