I had to do a bit of experimentation to find out what went where. Recorded here in case it helps someone and for when, inevitably, I try and do it again in a few months’ time…
So, not only are there 5 wires instead of 4, but the colour coding is very different too. Opening up the case to the nunchuk and looking at the PCB shows some convenient labels:
GND – brown
SDA – red
SCC – yellow
VDD – blue
J1 (seems to be connected to VDD) – white
I managed to break off the white wire at the PCB whilst I was prising off the hot melt glue to look at the labels, and the following worked without re-connecting it…
After testing on a breadboard, I soldered the wires to some headers for ease of use later.
With the above code red goes to Analogue 4 and yellow goes to Analogue 5. (Either connect the other two wires to GND and 5V pins, or the code allows for blue to Analogue 3 and brown to Analogue 2.)
Haven’t quite figured out what I’m going to do with this yet!