Need help with Motorola GM360/CM360 Radio

Our crane equipped by UHF and VHF radios with common PTT pedal and microphone.

Original UHF radio (ZODIAC Proline 400M) got faulty and we have tried to install/connect Motorola Radios GM360 and CM360:

  •    External MIC was connected to pin 2 (EXT MIC AUDIO) and pin 7 (GROUND).
    
  •    PTT Pedal was connected to pin 3 (DIG_IN1) and pin 7 (GROUND).
    

When we push on pedal (PTT) – we have TX (red led on radio is ON), but microphone was not working.

The voltages were measured between pins on rear side of Radios and compared:

  1. Original UHF ZODIAC radio (when it was fully operational).
    Voltage Radio ON, PTT not activated PTT activated, microphone works well
    Between COM – PTT 2,78 VDC 0,07 VDC
    Between COM – MIC 0,57 VDC 0,57 VDC
    Between PTT – MIC 2,2 VDC 0,57 VDC

  2. Original VHF HYTERA radio (fully operational).
    Voltage Radio ON, PTT not activated PTT activated, microphone works well
    Between COM – PTT 4,49 VDC 0,07 VDC
    Between COM – MIC 7,27 VDC 7,36 VDC
    Between PTT – MIC 2,77 VDC 7,38 VDC

  3. Newly installed UHF MOTOROLA CM360 radio (radio is long time on board).
    Voltage Radio ON, PTT not activated PTT activated, microphone doesn’t work
    Between COM – PTT 3,09 VDC 0,07 VDC
    Between COM – MIC 8,79 VDC 8,79 VDC
    Between PTT – MIC 5,69 VDC 8,8 VDC

Please advice why the external microphone does not work with both Motorola Radios (GM360 and CM360)?
These radio are not programmed properly? How we can solve this issue?