CAN bus help and advice

[Izzug]

time / date and other display settings like C or F are stored in the cdplayer

Totally agree, those settings are sent on the bus and the display picks them up. It looks like the cd player does not send the data out periodically, do you know the frame ID that the cd player uses to send the data?

[Izzug]

The circuit would be very welcome for me, though maybe too much for some forum members.

Aren't the three holes on the left meant for push buttons? I admit that in your photo they could be taken for bulb holders, but other pics (for example https://www.ebay.co.uk/itm/254529516933) show pcb tracks in them, which would be commoned together by carbon pads or similar on the ends of push switches.

Edit: inserted eBay pic for ref when the item is no longer listed.

Yep, the holes are indeed for push buttons, you are dead right the PCB tracks are 'made' by a conductive pad that would be fitted. Unfortunately my display does not have the buttons. So I fitted some in the hope that it would work, again unfortunately those buttons are not active / implemented on my display, I'm guessing that this 'feature' is for slightly different models that use the common PCB. I was hoping that was going to work. I can 'Read' the hardware and firmware for the display so again I'm guessing that the firmware could be model specific depending on the 'options' at build.