My 4 year old Garmin 76 keeps shutting off.

From the saved data when you backed it up on the computer. Use Garmin Express to transfer.

How to Backup User Data from GPS 72/76 or GPSMAP 76/76S

https://support.garmin.com > en-CA
It is recommended to occasionally back up the user data on your GPS 72/76 or GPSMAP 76/76S. User data includes waypoints, routes, tracks, and geocaches.

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  Transfer User Data From MapSource to a GPS 72/72H/76 or ...

  https://support.garmin.com > en-CA
  To transfer user data, such as waypoints, routes, and tracks from the MapSource program to these devices, some additional equipment will be required.
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  Manually Creating Waypoints on GPS 72/76 or GPSMAP 60 ...

  https://support.garmin.com > en-CA
  Press and hold Enter · Wait for the New Waypoint screen · Release Enter · Highlight the Coordinates field · Press Enter · Adjust the coordinates as desired with the ...
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  Backing Up Userdata (Waypoints, Routes, and Tracks) From a ...

  https://support.garmin.com > en-CA
  Before updating device software, it is recommended that you back up user data like waypoints, routes, and tracks. This should be done at regular intervals ...

Go to the Garmin.com website and update your unit's internal software. This might fix this problem.

You get a C8 and then a flashing code 76?

You may need a new power cord, I have the nuvi 250w and the cord is getting bad after a year. The battery will only run it for a short time.

KUDOS! Others with the same problem informed me that it is a softwear problem and to download the 4.0 version free on the Garmin web site....l'll do it ASAP and write again if it doesn't work...RG

Call Paloma and they will send you a new circuit board. We had the same problem. Our heater is a little over 2 years old. They said the error "76" is a circuit board issue where the tank is not communicating properly with the remote. The other solution they told us was to disconnect the remote and just let the heater run on the default.

before you throw it away try vchanging to new battery

I have run into the same problem and it may be related to the WAAS (Wide Area Augmentation System) feature. Try disabling this feature (under MAIN MENU / Setup). I used this receiver overseas (Asia and Europe) last year for 35 days straight with no problems. During this time WAAS was disabled as none of these satellites are visible overseas. The problem occurred intermittently prior to the overseas trip, and has reoccurred after returning. I was running into the same problem this past weekend and noticed the screen blanking out (with the vertical line) shortly after differential corrections were applied to the GPS signals. I disabled the WAAS and let the receiver run for over an hour. The problem did not return. Hope this helps.

Hello, I have had 7 Garmin units and 4 of them where streetpilots like yours.
You can try a reset of the unit. This will restore the unit and you might loose any favorites etc that you have stored. Here's how you do a reset.
"With the unit off, place your thumbnail in the groove located under the Garmin logo on the face plate, gently pull off the face place. Press the reset button and turn the unit back on."
Try this and see how the unit works. If it still gives you the same problem then your unit needs repair. I have sent in at least 2 units to Garmin for repair in the last 2 years.
Thanks