Thread: Using TMC in Garmin nuvi for free

The GTM 25 has a chronic problem in one of the connectors of data of cable terminal, I've had several with this problem. To be sure if it works, go to Diagnostics Page (Volume menu, press and hold the upper right corner of the screen). Choose the option Developer Info and post here the 3 Traffic screens to avaliation. In one must appear the subscription, in the other the radio stations TMC Traffic and in other information about tune and receptor. In the Traffic Status screen if nothing appears, move the cable and see if any information appears. If nothing happens after you move the terminals and cable in various positions, your cable be defective and may be used only to charge the batteries. Obviously it is worth remembering that the Traffic receiver only work with the cable connected to the vehicle's cigarette lighter socket.

Your problem is the 3.10 firmware that blocks the operation of the traffic.
Get Info on topic [Only registered and activated users can see links. ]
If you have a little patience I'll post step by step how to fix the problem. You have to downgrade the firmware and then install the subscription of your country..

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)

Besides the problem of blocking traffic signal by the firmware 3.10, your cable gtm25 also have a intermittent defect (or not connected to car plug), such that I mentioned in post 589, unfortunately. A blank screen, as shown in your image, denotes that the traffic receiver is not connected,perhaps only the energy part of the cable. If you managed to install the first firmware (Pasta1) correctly (100%), you should be able to install the rest. On this screen and connected at cigarette lighter plug of the car, move the cable in various positions, mainly at the end next to the gps, even begin to appear indicatives data on the Traffic Status Receive screen. At this point hold the position of the cable immobile that the second firmware must be updated. I have a cable gtm25 with exactly the same problem (prior to installation of v 3.10), so I can safely say that is an intermittent (hopefully) hardware contact defect, besides the locking of the 3.10 firmware