Swapping dcc decoders

[Jes TGU]

Can you change/replace the dcc decoder of a loco with the functions and other important things being lost?

For example, if I have a virgin pendolino with lights, and i replaced the decoder, would the lights still function and the loco run fine?

[Rog RJ]

Question makes no sense as posted.

Now amended.

Edited 10:36am

[Fishmanoz]

I’ll try to interpret for Jes Rog:

• functions come as part of the decoder and depend on the capability of the decoder. Therefore any specifics programmed into the previous decoder will need to be programmed again into the new one. There is nothing in the loco itself that knows or stores what the functions are
• if we use a Hornby TTS sound decoder as an example though, the function list is the same for any particular model. Therefore, if you replace like with like, the functions will be the same.

Does that answer the question?

[Jes TGU]

Question edited

[96RAF]

In answer to your basic question.

Lights (directional) are hardwired into the loco circuitry to operate from F0 of the decoder. Function 0 is universal across all decoders, so you can swap different decoders loco to loco and the directional lights will always work on F0.

As Fishy says what each of any other functions does (say TTS sound) is hard programmed into the decoder at manufacture and listed in the associated blurb. This ‘intelligence’ stays with the decoder.

[Fishmanoz]

To clarify Rob’s, the hard wiring for the lights in the loco is to accept the universal F0 in all decoders and connects to the white (forward) and yellow (rear) wires in combination with the common blue return wire.

So when you put in a new decoder, the lights will work as before. With one tiny proviso - the decoder is set to 128 speed steps which is the default setting. If you were to reprogram the speed steps to 28 in CV29, then the lights will stop working.