Montana 700i keeps turning off

The cradle isn't the problem so don't accept a new cradle as the fix. It's a hardware fault in the unit it's self. Get them to add you to the list for a new replacement when the rectified ones become available.

I have been having this issue on and off for months now. I am updated to 10.90. I thought that the problem was gone now but had the GPS (750i) go off several times, a few times within minutes of itself. I also have had the screen lockup entirely. It is displayed but then you realize nothing is updating. I have it mounted in a powered cradle. It was navigating with Topoactive and CityNavigator maps on. When I would choose the trip computer dashboard, when I would go back to the map, from a minute to several minutes after, it would shut off. It made it very difficult to see the connection because of the time lag after switching  back to the map while navigating but after 6 hours of playing with this, it really seems to be correlated. I don't know if anyone else can try this to see if it happens to them also. I should point out that I thought that this problem was gone because of a trip from CT to FL and didn't see this happen. When I think back on this, it is probably because it it unusual for me to switch to the trip computer and probably didn't do that on the entire trip down. I did it a few times on the way back and eventually started to realize what I thought was happening. I have checked the error log and nothing was listed. I don't know how long the error log stays intact so I will try to look right after it shuts down when I try this again tomorrow.

I also had this random shutdown problem with my 700i (see my earlier post). I raised a warranty claim with Garmin and, as is my experience with Garmin generally, they stand by their products with excellent support. I exchanged multiple emails with Tech Support who asked various questions about the AMPS mount and the power supply and also wanted copies of error logs etc, but eventually they decided this was a hardware issue and replaced the unit. Please note, this was not a local dealer but Garmin UK.

I've used the unit multiple times since and (so far) no failures or shutdowns.

Thanks. I may have to do something similar. Today, I tried to repeat this, many times on the road and no success. I will wait to see what happens. I didn't make sense before, and it doesn't now. Thanks for your response.

Unfortunately Garmin Australia weren't overly helpful but I made it through to Garmin US and yeah after emails and logs, I was told it's a hardware issue and my unit would be replaced under warranty. Hopefully I'll get it soon.

I have same issue with my montana 700. Did they say anything about devices with expired warranty? Please advice a best way to contact them? Via support ticket or via e-mail? 

Open a support ticket.

I can't advise about the expired warranty, although this is a known issue so I would be optimistic. In my experience Garmin stand by their products.

I would raise a support ticket in the first instance, but I expect you'll end up exchanging emails with a tech support agent, which is what happened to me.

Whenever possible, choose the "chat" or "phone" options for support tickets. Based on forum posts, email can be something of a black hole. This is for the initial contact to open the ticket. After that, all bets are off.

We're very sorry to hear your Montana is shutting off randomly when inserted in your powered mount.

We're currently working on a solution for the device itself and hope to have these available soon, we sincerely appreciate your patience.

In the meantime, rather than using the mount to provide power to the Montana, you can plug in the microUSB cable from your vehicle to the Montana instead, which should hopefully prevent this issue temporarily.