Keep each speaker’s positive and negative pair together to avoid weak, out-of-phase sound.
Wiring reference - ISO 10487
Car Audio ISO Connector
A practical pin-by-pin guide to the standard car audio ISO connector — power and controls on block A, speaker output on block B.
Pin assignment
View from pin side| Block A · Power & control | Pin | Block B · Speaker output |
|---|---|---|
| Speed dependent volume | 1 | Right rear speaker + |
| Muting control | 2 | Right rear speaker − |
| Reversing light switch | 3 | Right front speaker + |
| 12V permanent | 4 | Right front speaker − |
| Automatic aerial | 5 | Left front speaker + |
| Illumination | 6 | Left front speaker − |
| Ignition / switched 12V | 7 | Left rear speaker + |
| Ground | 8 | Left rear speaker − |
Connector orientation
Numbers shown looking directly at the terminal face.
Block A
Power & control
1
3
5
7
2
4
6
8
Block B
Speaker output
1
3
5
7
2
4
6
8
Power & control
Speaker output
Permanent 12V retains memory; switched 12V turns the head unit on with the ignition.
Disconnect the battery’s negative terminal before changing or probing radio wiring.