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.

Power and ground


Wires with black stripes are for negative power:

Amplifier and Antenna

They have low electric current, which is activated when the radio is turned on.

Phone And Others

ISO 10487 Harness Adapter

ISO 10487 connector in car, fits into head unit
ISO 10487 connector in car, fits into head unit

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.

ISO 10487 connector pinout (plug side of male, wiring side of female)
ISO 10487 connector pinout (plug side of male, wiring side of female)


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 the 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)

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 typically green and C3 is generally blue in colour. The contact spacing is narrower than the other connectors, so the C connector is sometimes referred to as mini-ISO.

C1 (external amplifier)
1) line out left rear 4) line out left front
3) line out common ground 6) +12V switched (out)
2) line out right rear 5) line out right front
C2 (remote control)
7) receive data 10) +12V switched (out)
9) chassis ground 12) remote control ground
8) transmit data 11) remote control in
C3 (CD changer)
13) data in (bus) 16) +12v switched (out) 19) audio left
15) +12v permanent (out) 18) audio ground
14) data out 17) data ground 20) audio right

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 ten pins.


From 2000 and onwards, manufacturers, such as BMW, Citroën, 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 refers 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.[1] 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 have 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.

Quadlock A
1) right rear + 5) right rear - 9) I-bus (BMW) / CAN High 13) antenna (out)
2) right front + 6) right front - 10) phone mute / (Speed Signal) 14) illumination
3) left front + 7) left front - 11) tel on / CAN Low 15) 12V battery
4) left rear + 8) left rear - 12) ground 16) 12V switched

See also


  1. ^ "Quadlock pinout". PinoutGuide.