25 pin cable pinouts (series 2 and 3 tranceivers)

 PIN    DESIGNATION/FUNCTION
  1     Transmit Audio/ON - OFF Function
  2     Mobile/Transportable Select Line
  3     Ground (A + return), one of 2 black wires.  Both are required for proper
        operation
  4     Battery A +, one of 2 red wires. Both are required for proper operation.
  5     Ignition Sense Lead, green with red tracer
  6     Receiver audio to handset (RX High), pin 8 on the handset connector
  7     Ground
  8     Regulated +9.5 volts to handset, pin 2 on handset connector
  9     Ground
  10    Auxiliary Alert, yellow with black tracer, used to blow the horn or
        flash the headlights.  Provides a ground function. NOTE: 1/2 amps
        maximum current.  The recommended method is to drive a relay 
        (e.g. MOT 59K813674).  Ignition Sense, pin 5, must be low for this
        function to work.
  11    T-Data, one of the 3-wire bus lines, to pin 3 of the handset connector
  12    C-Data, one of the 3-wire bus lines, to pin 4 of the handset connector
  13    Ground
  14    Transmit Audio Shield
  15    Transmit Audio
  16    Battery A+, one of two red wires. Both are required for proper operation
  17    Ground, one of two black wires. Both are required for proper operation 
  18    R-Data, one of the 3-wire bus lines, to pin 5 of the handset connector
  19    Receiver audio to external speaker
  20    Ground for receiver audio (shield) to external speaker
  21    Manual test line.  When connected to ground, puts phone in test mode
  22    Ground
  23    Handset logic ground, to handset connector pin 1
  24    Handset audio ground, to handset connector pin 6
  25    Accessory ground, to external speaker

15 pin cable pinouts 

 PIN    DESIGNATION/FUNCTION
  1     Battery A+, red wire
  2     Transmit Audio / ON-OFF Function, a shared line between Audio (AC) and
        ground.  This line will toggle the ON/OFF status of the telephone.
  3     Ground (A+ return), black wire
  4     Ignition Sense Lead, green with a black tracer
  5     Receiver Audio (RX High), to handset connector pin 8
  6     Regulated +9.5 volts, to handset connector pin 2
  7     T-Data, one of the 3-wire bus lines, to handset connector pin 3
  8     C-Data, one of the 3-wire bus lines, to handset connector pin 4
  9     Digital Hands-Free Microphone / Manual Test.  When the pin is grounded,
        which can be done by shorting the two connectors of the Hands-Free
        microphone, the unit is enabled to work in TEST MODE.
  10    R-Data, one of the 3-wire bus lines, to handset connector pin 5
  11    Handset Logic Ground, to handset connector pin 1
  12    Speaker High \  
                      | -> Only on SKN4279A and SKN4277A
  13    Speaker Low  /
  14    Handset Audio Ground, to handset connector pin 6
  15    Auxiliary Alert, yellow lead with a black tracer, used to blow the horn
        or flash the headlights.  Provides a ground for the relay; maximum 
        current is 1/2 amp.  It is  *N O T*  recommended that this circuit be
        used to drive the horn or headlights directly.


Motorol Transcievers
_____________________
4500x,4800x,6800x,Etc.
______________________
Female 25 Pin                                Male 25 Pin
D-Connector                                  D-connector
To transciever                               To P.C.Parallel Port
          Pin                                     Pin
          1._____________________________________  4.
          2._____________________________________ 18.
                                     ___10k______ 13.
                                    / 
  ______4+5._______________________/____10K______ 12.
 |       12.____________________________________/
 |       11._____________________________________ 13.
 |       18._____________________________________  1.
 |       21._____________________________________  2.
 |    ___14+17+20+23.____________________________ 18.
 |    |
 |    |___ -ve
 |
 |________ +ve 9 Volt