I measured values on pin A1 of the ISO 10487 connector.

Here you are the measured values:

It can be calculated more accurate values with "distance = speed x time" formula. It seems the distance is around 0,105m. I this case the duration are the followings:

The arduino program for the measuring was the following:

/*
ISO 10487 defines a standard for connectors for the head unit to the car's electrical system, consisting of a system of four different connectors typically used in head units for car audio.
   Power (A)
     +-----------------+
     | |1  |3  |5  |7  |
    _|                 |
   |_  |2  |4  |6  |8  |
     +-----------------+
   
   A1 Speed signal
   A2 Phone mute
   A3 Not connected
   A4 +12v battery
   A5 Antenna motor
   A6 Illumination
   A7 +12v switched
   A8 Ground

***

             +---+
      +------|USB|------+
      |[ ]J1 +---+      |
      |( )TX0     RAW( )|  RAW
      |( )RXI     GND( )|  GND
 GND  |( )GND     RST( )|  RESET
 GND  |( )GND     VCC( )|  VCC
      |( )2        A3( )|
INT0  |( )3   /\   A2( )|
      |( )4  /  \  A1( )|
      |( )5  \  /  A0( )|
      |( )6   \/   15( )|  SCK
      |(X)7        14( )|  MISO
      |( )8        16( )|  MOSI
      |( )9        10( )|
      +-----------------+
           ProMicro
*/

int SignalPin = 7;
unsigned long duration;

void setup()
{
  Serial.begin(9600);
  pinMode(SignalPin, INPUT_PULLUP);
}

void loop()
{
  duration = pulseIn(SignalPin, LOW);
  Serial.println(duration);
  delay(1000);
}

I forgot to mention that there was a 4N25 optocoupler on pin7. I will attach some pictures about my prototype board soon...