TMC in TomTom Carminat does not work anymore

TMC used to work fine for 14 months, but 5 weeks ago automatic TMC stopped working. The green dot is still there, but no traffic information is shown.
My Renault dealer solved it by using the manual option, but a manual frequency works for some hours, then it drops, and the next day I have to enter a new manual frequency again.
Especially during the holidays I want to have an automatic TMC frequency being chosen.

Any clues?

Thanks,

driver

Should be under warranty and you dealer should sort it out with TT.
Seems to me like the TMC code tables are missing - or did you install a new map by any chance?
Check in your map folder for the files "tmccodes.dat" "traffic.dat" and "tmctable.ttd" - if they are missing you will have trouble with TMC, same if the files are damaged.

All those files are present. I did install a new map (870), but TMC did work right after that for 2-3 weeks. Also when using my old map TMC does not work properly, or using another new 870 map it does not work correctly.

Sound like a faulty TMC module in that case.
I don't know if the antenna is build in, comes from the radio or is seperate, but I suggest you tell your dealer about it.
They sgould be able to check it and if necessary replace the unt.