The pinout for the DIN connector going to the external amplifier is given below. I believe it to be consistent for all Volvo CR units (and possibly TD units too?). Certainly the external amp DIN pinout between a CR-702, CR-905, CR-906, and CR-4024 are all verified as being cross-compatible.
Please note that I have not personally verified the displayed pinout to be correct - the only way to do so is to play some audio and use an oscilloscope on the audio signals. I have no reason, however, to doubt that the pinout given is correct.
Also note that the CR-4024 9-pin connector (the one providing permanent & switched live, as well as ground) only 'breaks out' the two front speaker outputs (FL+/- and FR+/-).
Finally, you may need to rotate the image to match the orientation of the connector on your unit - pay attention to where the notch is for the DIN cable 'latch' and use that as a reference for the connector's orientation.
Alternative Link:
https://drive.google.com/file/d/1CMy...ew?usp=sharing