Unlocking Your GPS

Garmin GPSs will display vector (point and lines) maps from any source. However, they are locked to only display official, Garmin provided raster (image) maps. Unfortunately there isn't an approval process for 3rd party map providers like CalTopo - so there's no way for me to provide JNX maps that will work out-of-the-box. In order to use CalTopo's downloadable JNX maps, you need to unlock your GPS to work with all JNX files regardless of origin. Obviously this is not something supported or approved by Garmin.

To unlock a GPS, you need to:

  1. Download the latest firmware for it.
  2. Download a firmware patcher.
  3. Patch the firmware to create an "unlocked" version.
  4. Install the new, unlocked firmware onto your GPS.

Both the patcher and links to the latest firmware versions are available from http://whiter.brinkster.net/en/Versions.shtml. The patcher is a windows-only program; start it, select the file you want to patch, and it will create a new copy with "patched" in the name.

To install a new firmware file, first make sure you have good GPS batteries. Then rename the file to GUPDATE.GCD and copy it to the Garmin folder on your GPS. It should now be located at [GPS Drive Letter]:\Garmin\GUPDATE.GCD. Unplug the GPS, turn it on and you should see a "verifying firmware" message or similar.

Please note that I am a map provider only. Unlocking your GPS is risky, and you alone assume that risk. I am not associated with the firmware patcher and have no responsibility for or control over it. I cannot provide tech support for its use - you are responsible for figuring out how to patch and install firmware.

Unsure? You can download a sample map and take it for a test drive. With locked firmware, you will see an "Invalid JNX File" error message on startup. With unlocked firmware, you'll have aerial imagery between 44 N, -117 W and 46 N, -116 W.