Thread: Using TMC in Garmin nuvi for free

Below some procedures to downgrade of the 3.10 firmware in GTM 25 and 35 cables, to unlock the operation of traffic. This firmware appears as the option "Firmware Update for GTMxx Traffic Receiver Type 3" in WebUpdater or Garmin Express. Some versions of GTM25 and 35 are not affected (blocked) by this firmware.


1. Download the contents of the link and unzip it (download the the file attachment) [Only registered and activated users can see links. ]

2. Connect your GPS to your computer and navigate to the folder .System which is the internal memory of the GPS (enable system hidden files and folders of the Windows to view it).

3. Locate the folder RemoteSW and copy the contents of Pasta1 to it (a file 0060901..gcd will be overwritten)

4. Unplug of the computer and turn on the gps. When completed the Initialization connect the GTM25/35 cable to the vehicle lighter plug and and gps. Within moments the firmware must be updated with the progress appearing on the screen (+- 30 seg).

5. Disconnect the GTM cable and connect the gps to the computer.

6. Copy the contents of "Pasta2" to the folder RemoteSW, as in item 2.

7. Repeat the steps in item 4.

8. The Traffic should operate (if the subscription is correctly installed)