I've moved your thread over to the Sound (and Intercom) forum, please do
drop back to the New Members Board to introduce yourself.
The pinout listed in that other thread is accurate, the challenge is working out how the Motorola device is wired, colour codes are at the whim of the manufacturer...
If it's assembled with screws, then opening up the other end might be a worthwhile step. Otherwise get out a multimeter on ohms and start looking at resistance on
wire combinations.
With 4 wires, you will PROBABLY have a pair for mic and a pair for
speaker, but you MIGHT have a common
ground for all of it, and single wires for mic,
speaker and
PTT.
***This is a general approach, see note below***
The
speaker wires will be the easiest to find, look for a DC resistance in the order of Ohms.
Then I'd probably go looking for
PTT, see if holding down the
switch shorts or changes any of the resistances you found in looking for the
speaker (so write them down as you go).
You should then be able to go through a process of elimination on the mic.
But since you have a working mic input, you can change your approach. What resistance are you seeing between the 2 non mic wires?
What about between
current mic
wire 1 and each of the others and again with mic
wire 2?
Repeat with a rubber band holding the
PTT switch down (or a willing volunteer)