396 goes off and on by itself while navigating.

[Fxwheels]

Right, it has to do with power delivery.
I connected it to the bike and started to monitor the battery indicator in the upper right corner on the home screen ("Where To/View Map"). This indicator you don't get to see while navigating. So I've noticed that power is jumping on and off. Tried different cables - same thing.
Looking at the Power Source Info, Ext Volts indicator each time upon reconnecting jumps from 36NN to 49NN (last 2 digits are always changing), and Batt Volts are at 38NN.
Connected the cradle. Jumps on/off again, and even in more rapid pace. The reading is: Ext Volts jumps from 36NN to 51NN (but mostly 36NN), and Batt Volts is 36NN.
Connected to the laptop - not a hiccup. The power is always on. No interruptions. Ext Volts indicating steady 37NN and Batt Volts 37NN.
But the main thing is that the power is on/off when in cradle or USB connected.
Leads me to believe there's something with a power supply.

[Fxwheels]

I didn't have chance to test it out on a full day ride on the bike, but did connected it in the car's usb socket while was driving for about an hour, and the unit never blinked. The battery showed steady "lightning" sign (battery charging) without disconnecting/reconnecting issue and all the readings were steady.
So my suspicions on the bike's weak power delivery are standing. Next time I'll try using the socket which is connected thru the ignition instead of the one connected directly to battery which I've used before.

[jfheath]

Yes - you can do that, but you could also find a way of powering a USB cable from the bike's battery.

Since the USB cable works without fault in the car, that would be a surefire way of determining whether it was your bike's power supply or whether it was the bike's Zumo cradle that is at fault.

I guess that the Zumo's car cigarette lighter plug has some circuitry to knock the voltage down, so I'm not sure how you would do this. I have a couple of 2A USB sockets powered from the battery (fused and relayed), in my top box so I cna charge things on the move if I need to.

[Fxwheels]

On the latest ride it was connected to a different USB socket (the one thru the ignition and maybe the USB itself was more powerful than one I used before, I don't know) and the connections were not interrupted. The same as I described before with the USB in the car.
I've concluded that the weak power delivery was causing the problem with the nav behaving as it was.

[jfheath]

Brilliant ! - Well done for sticking at it. Once you have the answer, it all seems rather trivial compared to the amount of time and effort that you have to put in to sort it out.

[Wingincamera]

New to the forum, and having the same problem with my 396 mounted on a Goldwing using the Garmin cradle. At first, I thought it was maybe overheating, but even on cool or rainy days, it did the same thing. The contacts were good. Because of an injury, it had sat unused for about six months, into the cold winter. This week we were on a car trip and tried using the 396 in the car plugging it into the USB cable. Same problem, although I did not charge the internal battery first. Later with the battery fully charged it still goes off and on while navigating, sometimes not turning back on at all. A little frustrating. We end up using our cell phones for navigating, which works when a cell tower is available.
I thought I would my name to list of those having this issue.

[jfheath]

See the post from FxWheels, 3 posts up.

To charge properly the Zumos need a 2 amp power supply, and need to be fed Via the correct cable. Many produce less than this.
USB cables are not all the same, even if they have the correct ends.

[Fxwheels]

New to the forum, and having the same problem with my 396 mounted on a Goldwing using the Garmin cradle. At first, I thought it was maybe overheating, but even on cool or rainy days, it did the same thing. The contacts were good. Because of an injury, it had sat unused for about six months, into the cold winter. This week we were on a car trip and tried using the 396 in the car plugging it into the USB cable. Same problem, although I did not charge the internal battery first. Later with the battery fully charged it still goes off and on while navigating, sometimes not turning back on at all. A little frustrating. We end up using our cell phones for navigating, which works when a cell tower is available.
I thought I would my name to list of those having this issue.

It is Zumo power problem. You need 2 things: good quality usb cable and even more importantly the right amp usb socket. To check if the power is steady, just connect the cable to 396 and watch the very first screen battery icon. If power jumps on/off, you see the battery charge indicator showing it. If icon is steady all the time, than you got the right power from that usb socket.
I never had luck using the cradle, although cradle connections checked to be all good. It was hard wired to the ignition, later to 12v socket, and later to BMW 12v native socket when I rented a bike in Europe. Nothing worked. BMW socket was the worse. At one point I didn't notice when the battery almost ran out and it went to a power saving mode. Couldn't see display in the sunlight. Good thing I had a backup nav with me.
Try experimenting without the cradle but rather just directly using the usb cable. That's how I have it on the bike. When it works, maybe you'll use that socket to connect the cradle. I don't see how to connect the usb cable to the cradle and never bothered with it.

[twowheelstom]

A similar thing happened to me while riding recently and turned out to be caused by one of the brass sprung power pins in the cradle getting stuck in. When the unit lost cradle power it reverted to internal battery power but the screen was too dim to see, however vocal directions through the headset continued to be audible. Subsequent repair was simple.

how did you repair it?

[Wallace]

I've been plagued by this problem even after my post in Sept 22 and today I think I've cured it.

Basically the plug is only held in by a tiny screw to the cradle and there is next to no flange surfaces on the plug to stop the plug moving in the cradle, hence causing an intermittent connection.

What I done was scrounge a piece of monofilament fishing line about 0.5mm diameter and wrap this around the plug flanges to effectively bring the plug 0.5mm forward and make better conta t with the Zumo power pads.

Here's hoping it lasts.