Headlight cleaning system explained – structure, function and troubleshooting

Headlamp cleaning systems improve visibility in the dark and prevent dazzling of oncoming traffic through stray light. On this page, find out about the structure of headlamp cleaning systems and how they work. You can also find useful tips here on using these safety systems along with information on troubleshooting in the event of malfunction.

The following technical information and practical tips have been compiled by HELLA in order to provide professional support to vehicle workshops in their day-to-day work. The information provided on this website is intended for suitably qualified personnel only.

Headlamp cleaning system

Headlamp cleaning: Deflection and absorption of light beams by particles of dirt — Deflection and absorption of light beams by particles of dirt

Headlamp cleaning: Influence of dirty headlamps on driving safety — Influence of dirty headlamps on driving safety 1. Clean headlamp: Maximum visibility, no glare 2. Dirty headlamp: Less visibility, increased glare

Headlamps which provide intensive light are more prone to glare through build up of dirt. For this reason, the legislator prescribes headlamp cleaning systems for such powerful lights, as well as automatic headlamp leveling . The cleaning principle of a "water jet" has long replaced the "wiper" principle for headlamp cleaning.

Clean headlamp

Maximum visibility
No glare

Dirty headlamp

Less visibility
Increased glare

Headlamp cleaning system (hlcs) for cars

Headlamp cleaning system for a car: System design — System design of a headlamp cleaning system: 1 Timer, 2 Water reservoir with motor pump, 3 Nozzles or telescopic nozzles, 4 T-piece or central valve

Headlamp cleaning system for a car: Circuit diagram — Circuit diagram of a headlamp cleaning system

A complete HELLA headlamp cleaning system is made up of the following components:

Whirl chamber nozzles with a range of jet stream patterns in stationary or telescopic extendable nozzle systems
Switching valves / central valve
Hose assembly with plug-type system
Water reservoir with centrifugal pump
Triggering: Electronic timer or relay

Cleaning principle

Headlamp cleaning system: Function — The function of telescopic nozzles: The impact of the "micro drops" on the cover lens has the effect of loosening and rinsing off the dirt.

Function using the example of a telescopic nozzle system

The cleaning fluid is sprayed at high pressure in the form of cone-shaped drops onto the headlamp cover lens. The cone-shaped drops are formed by means of special whirl chamber nozzles.

The headlamp cleaning system is usually triggered together with the windscreen cleaning system. Every time the driver activates the windscreen washers, the headlamps are automatically cleaned at the same time. This coupling only takes place when the lights are switched on. When the centrifugal pump is triggered, this presses the water into a cylinder, the piston of which has a nozzle head attached and is extended against a pressure spring, bringing the nozzles into their working position.

Until the working position is reached, a valve ensures that the movement only is carried out first without any water escaping from the nozzles. When the working position has been reached, the valve opens and water is sprayed onto the headlamps. Once the pump has been switched off, the return spring moves the piston back into its initial position. One washing impulse takes approx. 0.5 s for stationary nozzles and approx. 0.8 s for telescopic nozzles (due to the time required for extension).

Checking headlamp cleaning systems

If the centrifugal pump does not work (noise can be clearly heard during normal operation) when the washing function has been activated, the voltage supply including the fuse must be checked.

If the water spray cone is only one-sided or extremely weak although the pump is working, this could be caused by the following:

Inverse polarity of the motor pump:
Check the polarity, since centrifugal pumps can work in both directions of rotation but with different hydraulic power.

System is not bled:
Bleed the system completely by activating the system several times without a break.

Hose is kinked or leaking:
Check the routing of the hose and change if necessary. Seal leaks and/or repair hose.

Nozzles or valves are blocked:
Remove foreign particles by rinsing the system.

Component parts are frozen up:
Increase amount of anti-freeze. Freezing will not damage the components, however.

If cleaning efficiency is still not as good as it should be, check the nozzle setting and/or set according to manufacturer's specifications.

Headlamp cleaning system obligation

For europe the main requirements are as follows:

The cleaning systems are subject to type approval according to ECE R45 with regard to their cleaning power.
The fitting of such systems when gas discharge lamps are used has been compulsory since 1996 in compliance with ECE R48.
Water reserves for 25 or 50 cleaning cycles (class 25, class 50)
Cleaning efficiency of > 70% on a headlamp that is dirty to such an extent that only 20% of the original luminous flux is available
Functional capacity up to 130 km/h and from –10 °C to +35 °C