C40x
The C404 and C405 plugs are the door connectors on the vehicle Loom. They allow the door wiring to be disconnected from the rest of the vehicle, so that the doors can be removed easily.
The plugs on the A-pillar. The C404 connector is for the right door and the C405 connector is for the left door. The male portion of each connector is on the cabin side of the vehicle, and the female portion of each connector is on the door side of the vehicle.
Because the E30 was primarily designed for the domestic German and export US-markets, the wiring is designed around a driver seated on the left, and therefore the C405 plug carries more info than the C404. Where possible, C404 equivalents have been listed in the table.
Removal of the male portion of the connector is straight forward. Pull back the rubber boot to expose where the female portion of the connector connects to the male portion of the connector. Pull the female portion connector away from the male, then use a flat-head screw drive to release the three clips that hold the male portion of the connector to the cabin.
The wiring that passes through the C404 and C405 forms a key part of the Electrical system.
| C404
Pin |
Colour | Function | To | Image |
|---|---|---|---|---|
| 1 | Green/Black | Electric Mirror | Fuse 19 | 
|
| 1 | Blue/Black | Electric Mirror | Mirror Motor | |
| 2 | Blue/White | Electric Mirror | Mirror Motor | |
| 3 | White/Black | Electric Mirror | Clutch Solenoid | |
| 4 | Brown | Electric Window switch | Ground G200 | |
| 5 | ||||
| 6 | ||||
| 7 | ||||
| 8 | ||||
| 9 | Blue | Central Locking | Door Locking Motor - lock | |
| 10 | White | Central Locking | Door Locking Motor - unlock | |
| 11 | Yellow/Blue | Central Locking | Microswitch - Lock | |
| 12 | Green/Blue | Central Locking | Microswitch - Unlock | |
| 13 | Violet/Blue | Electric Windows | ||
| 14 | Black/Blue | Electric Windows | ||
| 15 | ||||
| 16 | ||||
| 17 | ||||
| 18 | ||||
| 19 | Black | Central Locking | ||
| 20 | Grey/Green | Speakers | Tweeter | |
| 21 | Green/Yellow | Speakers | Tweeter | |
| C405
Pin |
Colour | Function | To | Image |
|---|---|---|---|---|
| 1 | Green/Black | Electric Mirror | Fuse 19 |
|
| 2 | Brown | Electric Window switch | Ground G200 | |
| 3 | Red/Black | Central Locking | Fuse 27 | |
| 4 | ||||
| 5 | Blue/Black | Electric Mirror | Mirror Motor | |
| 6 | Blue/White | Electric Mirror | Mirror Motor | |
| 7 | White/Black | Electric Mirror | Clutch Solenoid | |
| 8 | Brown | Ground | ||
| 9 | Blue | Central Locking | Door Locking Motor - lock | |
| 10 | White | Central Locking | Door Locking Motor - unlock | |
| 11 | Yellow/Blue | Central Locking | Microswitch - Lock | |
| 12 | Green/Blue | Central Locking | Microswitch - Unlock | |
| 13 | Violet | Electric Windows | ||
| 14 | Black | Electric Windows | ||
| 15 | Red/Black | Central Locking | Central Locking module | |
| 16 | Brown/Blue | Central Locking | ||
| 17 | Red/Brown | Central Locking | Inhibitor Switch | |
| 18 | Green/White | Interior Light | Interior Light delay timer | |
| 19 | Brown/Green | Interior Light | Door Handle switch | |
| 20 | Grey/Green | Speakers | Tweeter | |
| 21 | Green/Yellow | Speakers | Tweeter | |
