Follow the flow chart to turn on audio assist. If your wire is broken you will hear nothing, if not your will hear “Welcome to Audio Assist”. To exit Audio assist press 0.
If this is a recent release, it will have a Loksound 4.0 decoder in it. If configured to North American standards, F8 will start the engine sounds. If European configured, F1 will start the engine sounds.
(Edit) - Maybe I misunderstood … thought he had installed a TCS stay alive to the original decoder - I believe I am mistaken on that now that I re=read the opening post …
I looked at the link and the information there in. It appears that F8 pressed 1X is a mute/unmute. I suggest that the OP check to see if the sound is muted first, and then follow the flowchart.
F8 also is how you toggle between light and sound mode, it could be it’s in light mode and so sounds aren’t responding. Try pressing F8 to mute-unmute as noted earlier, then try pressing it twice quickly to switch from light to sound mode. If that doesn’t work, press F8 4 times to enter Audio Assist. If you hear the lady talking, the decoder is working and the speaker is OK.
If all else fails, you can try a factory re-set. It’s a little complicated compared to other decoders, but the instructions for the TCS decoder shows how to do it. You can find it online too.
Could also be a blown speaker, or output amplifier in the decoder. I once blew the output amp on a Soundtrax decoder. Sent it back, and they replaced it.