Design

Design

Headlight system Bi-Xenon (model year 2012-)
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 headlamp levelling.

Xenon vs. Halogen
Xenon:
- higher color temperature, which produces a whiter light
- better reflection of road signs and road markings
- lower power consumption (approx. 65% lower).

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.

Bi-Xenon lamp




The light source consists of a discharge tube surrounded by a glass that filters out harmful UV radiation.
- The discharge tube is filled with a blend of chemical compounds, including the inert gas Xenon.
- An electric arch is created through an electrical discharge between two tungsten electrodes.
- Because the lamp does not have a filament, it is less sensitive to bumps and vibrations.
- Bulb designation: D1S (For S60 (11-) and V60, D3S is used.).
- Power consumption: 35 W.

Caution! The Bi-Xenon bulb contains mercury (less than 0.5 mg), thus classifying it as hazardous waste. Hazardous waste must be handled in accordance with national legislation. See also Volvo Car Corporation's "Waste Management Guidelines for Dealers."

Position sensor, headlamp levelling




Vehicles without Four-C (Continuously Controlled Chassis Concept) have two position sensors for automatic headlamp adjustment. The headlamps are adjusted vertically based on load and road conditions to reduce the risk of dazzling.
One position sensor is located next to the rear axle and is connected to the left-hand rear control arm by a linkage system. The other position sensor is next to the right-hand front axle and is connected to the right-hand front control arm by a linkage system. This linkage system affects the sensor, allowing the angle of the car to be gauged.
The position sensors are directly connected to the Central electronic module (CEM). Each position sensor has three connections. Two are used for power supply and ground. One is used for signals on vehicle angle. When the ignition switch is in position II, level control is active and the sensors are used to calculate the average vehicle angle. At about 4 km/h (2.5 mph), dynamic level control is activated, which also makes quick corrections during acceleration and braking. In addition to vehicle speed in excess of about 4 km/h (2.5 mph), darkness is required.
The position sensor can be calibrated using the diagnostic tool. The calibration is saved in the Central electronic module (CEM) and must be performed again upon replacement of the control module or position sensor.
Vehicles with Four-C (Continuously Controlled Chassis Concept) use the signal from the suspension module (SUM) instead.
The position sensors can be diagnosed via the Central electronic module (CEM).

Left headlight control unit (LHCU) / right headlight control unit (RHCU)




The left headlamp control unit (LHCU) and right headlamp control unit (RHCU) handle headlamp levelling and active control of the light beam. Active control means that the light beam is turned out to the left or right. The light beam is turned out at varying degrees and rates depending on vehicle speed and steering angle.
Information is transferred between the left headlamp control unit (LHCU), right headlamp control unit (RHCU) and Central electronic module (CEM) via serial communication.
The lamp housing contains a sensor that indicates whether the light beam has been turned out to the right or left. The left headlight control unit (LHCU) and right headlight control unit (RHCU) send this information to the Central electronic module (CEM).
If there is no communication with the Central electronic module (CEM) or there is a fault in the left headlamp control unit (LHCU) and/or right headlamp control unit (RHCU), headlamp levelling and active control are disabled. The light beam then assumes its "limp-home" position (shortest beam length is used straight ahead).
The left headlight control unit (LHCU) and right headlight control unit (RHCU) can be diagnosed.
The control units are integrated in the headlamps. If a Left headlamp control unit (LHCU) or Right headlamp control unit (RHCU) becomes damaged, the entire headlamp must be replaced, for certain models.

High voltage unit (ballast)




High voltage is required to light the Bi-Xenon lamp.
- A high voltage unit is connected to each Bi-Xenon lamp. This transforms 12-V voltage to the approximately 24,000 V required to light the lamp. Once the lamp is on, voltage is lowered to the approximately 100 V required to keep the lamp lit.
- Each time voltage is supplied to the high voltage unit (from the Central electronic module (CEM)), 3 attempts, for 1 second, are made to light the Bi-Xenon lamp. If this voltage does not exceed 9.5 V during a time period of 200 ms, the lamp does not light. If voltage is too low, such as after a voltage-consuming cold start, the lamp does not light just because the engine is running and the alternator begins charging. A new attempt must be made to start the lamp by turning the light switch to the "0" or parking light position and then back to the low beam position.

Warning! Because of the high voltage it is important to follow the instructions for working with Bi- Xenon lamps and the high voltage unit!