atmurray posted several pictures of the harnesses and sockets on the back of his RHD AUDM HU, as well as the label in his thread here on LGT:
AUDM Ltd Ed Nav - A/V In, Vid Out & Sub Line Out
Model number (for RHD AUDM) is FZDA07MRHF2.
Also see these threads on liberty.asn.au:
Help with Reverse Camera!
How to: Ltd Ed Nav AUX In/Out, Sub Out
atmurray found this "Cord Convert" cable from Subaru, P/N H0010AG100 (not available in the US). Price is about USD $50 to $80 (depending on which country you find it). It connects between the HU's 24-pin socket and the car's harness, and adds RCA jacks for aux A/V input, video output, and subwoofer output:
He drew this wiring diagram, showing which pins it passes through from car to HU and which have the new RCA jacks and other wires:
Since this 24-pin socket is so similar to the one on 2008-up Impreza and 2009-up Forester, I strongly suspect that:
- The subwoofer output is balanced, mono. Pin 24 (labeled as a second "Sub Out Ground") is actually the inverted version of the sub output signal. Pin 12 ("Sub Out") is the positive signal.
- Pin 14 is likely simply a ground (since the Aux Enable input -- pin 9 -- needs to be connected to chassis ground).
We'll need to see the wiring diagrams to find out what pin 1 ("unknown") is. [ADDED:] Pin 1 is used for anti-theft security on these OEM Kenwood satnav HUs in some Subaru models (none in USA).