Light switch unit (684): Connection
The light switch is directly grounded to the body. The two pins of the lighting knob, the pin for front fog lights and the pin for rear fog light, are fed 10.2. V separately via a 1.2 kO resistor integrated in BCM (headlamp position has 1.5 kO). Voltage between each pin and ground is 0 V when the circuit is closed to ground and approx. 6 V when it is open (headlamp position 5.5 V). If the control module detects 10.2 V, it will be regarded as a break. The LEDs are grounded internally and are supplied with PWM from BCM. Headlamp levelling requires one pin for +15 and one for the output to the two headlamp levelling motors.
CONNECTOR PINOUTS REFERENCE
| Pin No. | Signal type | Description |
|---|---|---|
| 1 | Ground | Ground to the body. |
| 3 | Lighting | From BCM, power supply with PWM to LEDs |
| 4 | Lighting | From BCM. + supply with PWM to LEDs |
| 5 | Headlamp beam adjustment | To the headlamp levelling motors. Drop in voltage when the knob is turned to a shorter beam length. |
| 6 | Power supply, +15 | From dashboard main fuse box pin 8 |
| 7 | Headlamps | To BCM. Grounded two steps from knob's right end position (when knob points straight up) |
| 8 | Parking lights | To BCM. Grounded one step from knob's right end position |