Things you may need:-

Pen/Pencil & Paper

a Ampere/Volt/ohm meter (AVO) Commonly known as a test meter

Make a Shielded Probe

Make a probe with small crocodile clip and 100ohm resistor 12" wire. Solder the Resistor to the Crocodile Clip then solder the Wire to the other side of the Resistor, Bare about 1/4 inch of the free end of wire and Tin with Solder.

Draw your Microphone socket numbering the pins
write pin numbers in a list

using your Test Meter
What you need to find!
1. an earth connection (radio chassis)
2. a connection to the microphone
3. a connection to the PTT circuit
4. a connection to the Rx output (L.S or earphone) {Not always on the Mic)

To test for these you will need your test meter Set for Voltage a Range between 12V to 25v should be OK

Test all the Mic connections with a meter connected negative to the metal framework, look for a pins with voltage on them? what voltage is it ?

No Voltage! it could be Ground (Note pin No.)
switch meter to OHMS
Test Noted Pin with Ground if its Less than 1ohm thats Ground (Write it in)

Voltage found! It could be the
A. PTT line,
B. the power supply to a "Power Mic",
C. the bias for an Electret microphone.

Check the Voltage

result = 5v to 8v! Output for PowerMike
result = 0v to 0.1v Electret mic line (Mic Audio Write it down)

using The Probe described earlier

Test each of the Pins to Ground :-

If the TX fires up! you have found the PTT, (Write IT down !)

The idea of using the resistor is to protect the source of supply of this voltage, should it be capable of producing a higher current than would be safe.

Now to find out what sort of supply this is?

Using TX to Ground - Key up the TX - listen on a RX tuned to the same frequency. Touch the remaining wires with a finger, listen for a hum on the RX? Ok, that should be the Mic live wire, NOTE IT

if you want you can use the earphone socket on the rear of most mobile radios, if one does not exist do the following:-

Using a set of headphones and a 0.1uf ceramic capacitor, open the squelch of the receiver or cause it to receive a signal, touch the the remaining wire(s) when you hear the received signal? thats the Rx output, NOTE IT!

That deals with ALL the Needed Pins needed for packet operation, These are all that is supplied on 4 pin microphone connectors,

If your microphone has 5 or more, Other connections to multi-pin mic connectors can support scanning up/down stepping or band change facilities, again it should be a simple matter to test these lines with a meter, those that have voltage on, connect to ground with the Probe, see what happens, and make a Note of it!

its easy to solve just about any wiring problem using this method,

Never Direct short any pins until you actually know their function