My ancient 855

Certainly would try using the smaller JCV file as it is a simple test to determine if the large file is causing the problem.

I tried a couple of simulations on my 855 and so far everything seems OK. I seldom use my 855 any more, but do loan it to a family member now and then, so I keep it updated.

For my 2018.20, I have the map in internal storage with the large JCV, ASR and SRX files on SD. That combination seems to work OK for me.

@Melaqueman ... if you want to PM me through the contact form with the starting point and destination of the route causing the shutdown, I will do a test simulation on my 855 to see if I get the same results.

As you alandb, the 855 is not my primary GPS anymore. A few years ago I visited friends in Wichita,Ks. When I left there just around Kansas City my 3790 "crapped" out on me. Past experiences have shown me that many times if I ask for directions which are more than 5 - 10 miles from the persons location they have no idea how to get for example to Detroit. Two more days to get home and no paper maps. Finally spotted a sign for Knoxville,Tn which is usually on my route. Doing that added more than 200 miles to my route. I should have gone towards Cincinnati. Since then I carry the 855 as a back-up just in case. Now I have another choice my new car has a Garmin based Nav system, but not as easy as a Garmin to manipulate.

Anyway I hooked up the 855 to my computer and disabled the large JCV and re-enabled the smaller JCV. This is how I disable a file -D3060240A-.-j-c-v . This gives me the option to re-enable it without having to copy it from somewhere.

Anyway enabling the smaller JCV seems to have cured the 855 problem. Maybe it is a case of overloading the system using the large JCV.

Thanks for your kind offer alandb, if this would not have solved it I would have taken you up on your offer.

Another option would have been to do a hard reset to clear out the junk.

I do it faithfully after each map update.

Or maybe try re-installing the map?

Since you fixed your problem, this post may be moot but I thought I'd share my experience.

Although Garmin claims the 855 will work with an 8GB SD card, I had issues with erratic behavior on my old 855 when using one. The problems would appear after loading more than 4GB of data on the 8GB card.

I no longer have the 855 so I can't repeat these symptoms. I still however use the same SanDisk 8GB card in another unit without issue.

One of the first things I did was a complete map reload to the (CLONED) SD card.

The next I done was a factory reset as I mentioned.

I've been using an 8GB SD card for a few years and even the large JCV. Now the card has 2.67 GB on it with the small JCV file.

For whatever reason I assume that the large JCV was the culprit and since I removed it the problem has disappeared..

seems to work best if I keep the map files (gmapprom.*) in internal storage and put the large JCV and speech recognition files (ASR/SRX but not SRD) on SD. With 2018.20 that leaves about 600 MB of free space in internal storage.

Incidentally, I have always used a 8 GB SD card and it has never caused problems.

We've seen others encounter problems in the past with a faulty download & since you've already re-downloaded the maps & done a hard reset I suggest you re-download the JCV file.

Who knows but it might just be the solution