[scotta]

While surfing the web for information about my Garmin Nuvi 750, I've come across a number of undocumented or obscure features and tips. I thought I would summarise what I've found in case anyone is interested. Some are useful, others not so much.

These all work with my Nuvi 750 (currently at software version 4.60) but many apply to other models as well. Feel free to report successes and failures, or other discoveries, in this thread.

Note that some of this stuff, being undocumented and unofficial, may cause unforeseen and possibly permanent problems. Your warranty may not cover problems that result from doing some of the things that follow. Proceed at your own risk!

Satellite Status:
Press on the "Satellite Strength" bars in the upper left corner of main screen and hold for approximately 3 seconds. This will bring up a screen with the positions of the satellites and the signal strengths of those being received.

The screen also contains your current latitude and longitude, speed and elevation. Your current heading and the position of the Sun and Moon are also displayed with the satellite positions (north is up). The estimated positional accuracy is at the bottom. If you can see the Sun or Moon in the sky, you can align them with the display to form a crude "compass".

I believe this feature is only on wide screen units.

Raw Data Logging and Playback:
If your unit has the "Where Am I?" feature, bring up the "Where Am I?" screen. You can get to it by pressing the vehicle icon on the map screen or from "Where Am I?" in the tools. Press in sequence near the corners of the location text box: bottom left, top left, top right, bottom right. This will bring up menus that allow you to record raw navigation data to files and play the files back. You can discover how this works by playing with it, or maybe someone else will elaborate in this thread or a new one.

Any logs created will take up space in the unit's memory. You can access and delete them by connecting to a computer using USB. They will be in the Logs subfolder in the Garmin folder. Data for each session will be in a folder named with the date and time that it was taken (the same names you see using playback).

Doing a playback will automatically enable the "Screen Shot" feature, which will remain enabled until you disable it from Tools->Settings->Display.

System Info Pages:
Go to the Trip Information page (press the bottom left corner of the map screen). Press and hold the centre of the big speed indicator circle for approximately 6 seconds. This will allow you to view a number of system information pages. They're mostly only of use to the people who design and debug these things or possibly for technical support.

Diagnostic Pages:
Press the battery level indicator at the top right of the main screen (or in the blank area where it would be, if using external power) and hold for approximately 8 seconds. This gives access to a number of diagnostic screens. I've read that on some units you have to press the time instead of the battery level.

I'd be careful with these pages; some allow changing settings, etc. I found that my unit had to be powered down after exiting these screens and the time was reset. The correct time is restored the next time the unit acquires its position via satellites.

Touch Screen Calibration:
This is actually documented in my Nuvi's help menus under Troubleshooting->Touch Screen Not Responding but the exact procedure isn't clear. You have to press and hold anywhere on the screen while the unit is off. Then, while still holding, power on and slide the power switch to the "lock" position and leave it there. Continue to press on the screen for about 30 seconds until the screen calibration guidance appears.

MP3 Cover Art:
If your Nuvi can play MP3 audio files, it will display album art in the top right corner of the Media Player page. Nuvi's follow the convention that many audio players do. You put a JPEG file named cover.jpg in the same directory as the song that it applies to.

Normal Mode while connected to USB:
Other than using a Garmin power adapter, connecting to anything that provides power via USB will put the unit in "mass storage" mode. The unit will appear as a disk drive if connected to a computer. In this mode the display just shows the Garmin logo and a "computer to Nuvi" icon. The unit is locked and cannot be operated from the touch screen.

I've found ways to get my Nuvi into normal mode when plugged into a regular USB port. This is useful if you want to power the unit from USB but still use it while connected. It also lets you charge the unit without having the backlight on and the "computer to Nuvi" display (you just power the unit off while still connected). When running in normal mode it will not appear as a drive on the computer, but just draw power from the USB port as if connected to a Garmin power adapter.

Method 1: This works with Windows XP Professional (and probably other Windows versions). Put the power switch in the "locked" position. Use the "Safely Remove Hardware" icon on the Windows "Start" bar to "Safely remove Mass Storage Device - ...". The Nuvi will reboot and enter normal operation.

Method 2: This works with any powered USB port, even those non-Garmin AC and 12V to USB chargers. With the Nuvi showing the "computer to Nuvi" display, unplug the USB cable. After a short time the unit will start to reboot. When "Loading Maps ..." appears at the bottom, plug the USB cable back in. The Nuvi will continue to boot into normal mode.