Connectors for car audio

Several types of connectors for car audio systems are used.
Splicing wires.
Splicing wires used in car audio are mainly for power, ground, amplifier and antenna, speakers, phone and others.
Speakers.
Wires with black stripe are for negative power:
Amplifier and Antenna.
They have low amperage and it is activated when radio is turned on.
ISO 10487 Harness Adapter.
ISO 10487 was created in 1995 and 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.
Parts.
Part 1 of the standard is dedicated to "Dimensions and general requirements" and Part 2 to "Performance requirements".
Power (A).
The first connector A is always present, is usually black in colour, and contains pins for power-supply, off/on (typically controlled by ignition key), optional control for a motorised antenna and so on.
Loudspeaker (B).
The second connector B is for connecting four loudspeakers, front, rear, left and right, and is usually brown in colour.
Miscellaneous (C).
The connector C is optional. Sometimes it appears as one 20-pin connector, often red in colour, or it may be divided into three separate connectors which may be hooked together, in which case C1 is usually yellow, C2 is usually green and C3 is usually blue in colour. The contact spacing is narrower than the other connectors, so the C connector is sometimes referred to as "mini-ISO".
Note: ISO 10487 only defines the "physical" attributes of the connectors, "not" the pin/signal designations, which are "manufacturer-defined". 
The example above is oriented towards VW vehicles only.
Navigation (D).
The connector D is for satellite navigation systems. It has 10 pins.
Quadlock.
From 2000 and onwards, manufacturers, such as BMW, Citroen, Ford, Mercedes Benz, Peugeot, Volkswagen, Rover, Audi, SEAT, Opel or Škoda have sometimes started using a 40-pin connector instead, called the "Quadlock".
Unfortunately, "Quadlock" may not be the description used by manufacturers of the connector components. Therefore, searching for "Quadlock" components may be unsuccessful; for example, Molex refer to a typical component of the connector as "MOST Frame Receptacle Housing" (part number 986811001) .
The Quadlock connector consists of a block of 16 flat pins analogous to the two main ISO 10487 connectors. While the physical contact pins are the same, the pin allocation is not entirely the same, and the connector housing is not compatible. In addition to the 16 pins, like ISO 10487, there are minor connectors for optional equipment. They fit within the frame of the main connector, and has coding so that they cannot be interchanged. Minor connector B has 12 pins for audio output signals. Minor connector C has 12 pins for various audio sources such as CD-changers, MP3 players. 