Sorry to resurface an old thread, but I too am having similar (but not identical) issues with a recently -acquired DCC sound HST set.
Both the power cars are fitted with a TTS sound decoder and speaker. The unpowered trailer car lights are working perfectly as expected - turning on with function 0 and changing direction.
However the tail lights in the powered car come on when it is placed on the track (irrespective of whether function 0 is on or off). When I turn function 0 'ON', these lights go off, however the trailer car lights (which are working correctly) come on. I can manage to get both ends to light at the same time by putting the trailer car on the track, switching on function 0 and then placing the power car on the track. The power car, however, will not switch from showing tail lamps to headlamps. There is the slightest of flickers from the headlamps and cab light when the direction switch is pushed, but nothing more.
I've read through as many of these related threads as possible and tried the following, but to no avail:
- Resetting both decoders to factory settings by setting CV8 to '8' as per the Hornby TTS instructions.
- Checked CV29 to ensure correct speed steps selected
- Changed reverse direction in CV29
All other functions and motor control are working fine, but I've run out of things to try to rectify this.
Any help appreciated!