Safety
- In the event of a short-circuit on the high tension side the power supply cuts in less than 10 ms
- If the high tension circuit is broken (for example by a broken cable, blown bulb or no bulb in the bulb connector) the system attempts to activate the lamp for a time of 700 ms. During this time the high voltage is outside the ballast
- Approximate temperatures on the components during operation are; Ballast = 130 °C, Bulb holder = 170 °C, Bulb = 400 °C
- The glass body of the Bi-Xenon-lamp is filled with different gases and metal vapors which are under pressure. The lamp can explode as it is under gas pressure.
| WARNING | Follow the safety instructions and recommendations in VIDA carefully when working with high voltage. Use safety goggles when handling the bulb. Risk of explosion The electrical system must be switched off before starting work. Risk of burn injury. The components operate at very high temperatures. |
Scheme 546
- High voltage is required to light the Xenon lamp
- A high voltage unit is attached to each Xenon lamp. It transforms 12 V voltage to approximately 24 000 V, which is necessary to light the lamp. When the lamp is lit the voltage is reduced to the 100 V required to keep the lamp lit
- On each occasion that voltage is supplied to the high voltage unit an attempt is made to light the Xenon lamp. If this voltage does not exceed 9.5 V within a time span of 200 ms the lamp does not light. If the voltage is too low, after a power consuming start for cold start, the lamp does not light until the engine is running and the generator starts to charge. A new start attempt of the lamp must be made by turning the knob of the light switch till "0" position or parking lamp position and then back to low beam again.
| WARNING | Because of the high voltage it is important to follow the instructions for working with the Xenon lamps and high voltage unit |
Scheme 547
| 1. | Motor, high / low beam | Power supply via relay. Reconnected PWM signal provides information about the position of the reflector to the central electronic module (CEM). |
|---|---|---|
| 2. | Motor, headlamp range adjustment | Controlled by the central electronic module (CEM) using a PWM signal. |
| 3. | Position sensor | Inductive sensor which sends an analog signal (voltage) to the rear electronic module (REM) (Does not apply to vehicles with Four-C (Continuously Controlled Chassis Concept)). In vehicles with Four C the signal travels via the suspension module (SUM). |
| 4. | Ballast | High voltage regulator for switch and lamp. |
| 5. | Gas discharge lamp | Socket |
Scheme 548
| 1. | Central electronic module (CEM) | 4. | Motor, headlamp range adjustment |
|---|---|---|---|
| 2. | Rear electronic module (REM) | 5. | Suspension module (SUM) (vehicles with Four-C (Continuously Controlled Chassis Concept) only) |
| 3. | Position sensor |
An electric motor is controlled by the central electronic module (CEM) via a relay (ordinary high beam relay).
The motor drives a gear wheel which moves the reflector along its guides.
A sensor which detects the position of the reflector is connected to the motor.
- The electronics in the motor interprets the sensor information and generates a signal
- The signal is reconnected to the central electronic module (CEM).
If the reflectors are in the wrong position during high beam the reflectors are forced into a safety position
- the warning lamp (orange) lights in the driver information module (DIM)
- an error message is also shown in the display in the driver information module (DIM).
If the high beam is activated with the light switch in 0 position, the high beam is only activated as long as the high beam lever is activated for a high beam flash. The headlamp switch must be in the "on" position in order for the high beam lamps to remain active.
Scheme 549
| 1. | Ballast | 5. | Internal headlight edge |
|---|---|---|---|
| 2. | Motor, headlight levelling | 6. | Motor, high and low beam |
| 3. | Lamp contact, high voltage | 7. | Movable reflector |
| 4. | Lamp |
Bi-Xenon, a headlight system with moveable reflector, is based on gas discharge technology. The system combines high and low beam into the same lamp.
Due to legal requirements (regarding low beam) for this type of lamp, the vehicle must be equipped with automatic headlight levelling.
Xenon vs. Halogen
Xenon
- higher color temperature, which produces a whiter light
- better reflection of road signs and road markings
- has lower power consumption (about 2/3).
Good to know
- Daylight has a color temperature of about 5000 °K. The closer to natural light, the less strain on the eyes. Standard H4 bulb: 3200 °K. Volvo's gas discharge bulb: about 4200 °K.
- With the Bi-Xenon system, high and low beam generates the same light color. The human eye thus has an easier time adjusting to switches between high and low beam.