DON'T MISS OUT!

With our free newsletter, every two weeks HELLA will provide you with the latest news from the HELLA TECH WORLD

Stay tuned!

Show additional information on our newsletter Hide additional information on our newsletter
 

With our free newsletter, every two weeks HELLA will provide you with the latest news from the HELLA TECH WORLD, such as:

  • New vehicle-specific repair information
  • Technical information – from basic knowledge to diagnostics tips
  • New products
  • Marketing campaigns and competitions relevant for workshops

For this, all you have to do is enter your e-mail address. If you would like to unsubscribe from the newsletter, please click here.

Signal lights in cars

Here you will find useful information and handy tips relating to signal lights for cars.

Signal lights have an important safety function. They demonstrate deceleration and a change in direction of the vehicle, and make the vehicle more visible to other road users when it is dark or during poor visibility. On this page, you can find out how signal lights are structured, and what technology is behind new signal systems. Here you can also find the most common causes of failure for signal lights, tips for troubleshooting, and information regarding important regulations.

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

 

CAR INDICATOR SIGNAL LIGHTS: STRUCTURE

Exterior lights – whether attached at the front, side or rear of the vehicle – provide information for other road users through their signals and are thus responsible for safety on the roads to a substantial extent.

A conventional passenger car signal light basically consists of three assemblies: The bulb holder, the housing, and the cover lens.

 

  • The bulb holder positions one or more light sources correctly in relation to the optical system of the light.

 

  • The housing contains the reflectors which are usually molded.

 

  • The cover lens is responsible for light distribution through additional patterned structures.

 

In order to meet the photometric requirements, the light from the light sources has to be collected and directed, deflected, and distributed. Several optical component parts are used for this purpose.

Signal lights: Optical systems with bulbs

Optical systems with bulbs

ASIGNIS® – ADAPTIVE SIGNAL SYSTEM: FUNCTION

All the functions in a rear light only work on one brightness level, no matter whether they are switched on during the day, at night, or on a bright foggy morning. The only current possibility of adapting the lights to adverse weather conditions is the rear fog light. This is often used incorrectly, however, and leads to irritation. There is no additional information conveyed about whether the brakes are only being applied lightly or slammed on, for example.

 

Thanks to ASIGNIS®, the individual signal lights in a rear combination lamp (brakes, direction indicator etc.) can be adapted to the current situation. Depending on weather and visibility conditions the light intensity of the signals (e.g. brighter during the day and darker at night or with the braking signal) can be varied.

 

The requirement for differing braking signals can either be met by means of a larger signal area, an increase in brightness, or the addition of an increased flashing frequency. The stop light is activated in three stages dependent on deceleration: The greater the deceleration, the more LEDs light up. In the case of a hard stop, one part-array of the red stop light flashes as an additional warning function.

TIPS FOR DEALING WITH SIGNAL LIGHTS: PRACTICAL TIPS

In many vehicles, the light sources are controlled via pulse width modulation (PWM). This has several advantages for the vehicle lighting. For one thing, the same bulbs can be used for different functions, and the service life of the bulbs is increased.

 

The rear lamps of the Golf V also use PWM. PWM allows the use of a 21 W bulb both for the stop light and for the tail light. The pulse width is modulated in such a way that the 21 W bulb has almost the same luminous flux as a 5 W bulb. If the brake is now actuated, the turn-on time is so long, that 13.5 V is present at the stop light, and the 21 W bulb provides the full luminous flux (see illustration). Once the brake is released again, the voltage returns to 5.74 V.

 

When replacing bulbs in signal lights, the information and specifications of the manufacturer must always be adhered to. If an incorrect bulb is used, there is the danger that the required luminous intensity will not be reached.

FAULTY SIGNAL LIGHTS: SYMPTOMS

A faulty signal light can be detected from the following symptoms:

  • No signal is emitted for individual functions e.g. stop light. This leads to an increased safety risk, particularly during night-time driving
  • The indicator lamp on the dashboard lights up (failure monitor, if present)
  • Two lighting functions light up e.g. direction indicator and tail light

CHECKING SIGNAL LIGHTS: TROUBLESHOOTING

If a signal light fails, there are always several possible causes. The following points should be noted when troubleshooting:

  • Check the light sources and replace if necessary
  • Check the bulb holder for corrosion and contact interruption
  • Check the voltage supply including fuses
  • Check the plug-type connection for corrosion and mechanical damage
  • In vehicles with PWM, check the signals with an oscilloscope/diagnostic tester.

SIGNAL LIGHT REGULATIONS: GOOD TO KNOW

Due to the scope of the statutory regulations, only the most important are explained here. The following regulations contain all the relevant information about signal lights, their properties, and uses:

 

76/759/EEC, ECE-R6, StVZO § 54
Direction indicators front, rear, and side

 

76/758/EEC, ECE-R7, StVZO §§ 51 and 53
Marker lights and tail lights front and rear

 

77/540/EEC, ECE-R77, StVZO § 51
Parking lights front and rear

 

ECE R87
Daytime running lights

 

77/539/EEC, ECE-R23, StVZO § 52
Reversing lights

 

76/758/EEC, ECE-R7, StVZO § 53
Stop lights

 

77/538/EEC, ECE-R38, StVZO § 53d
Rear fog lights

 

76/760/EEC, ECE-R4, StVZO § 60
License plate lamps

 

ECE R3
Reflex reflectors

Direction indicators front, rear, and side
Number at the front Two
Number at the rear Two or four
Number at the side
(optional)
One per side
Colour Amber
Height position Between 350 mm and 1500 mm permissible
Width position Max. 400 mm from the outermost edge of the body. At least 600 mm apart
Side position Installation height between 350 mm and 1500 mm and max. 1800 mm from the front edge of the vehicle
Electrical circuit An electronic warning flasher unit is made up of a pulse generator which switches the lights on via a relay. In addition, it also has a control circuit which is dependent on current and changes the flashing frequency in the event of light failure. The frequency of the flashing signals is between 60 and 120 per minute. All the direction indicators on the same side of the vehicle have to work synchronously.
Switch-on control Green indicator lamp
Miscellaneous Depending on the requirements, there are different functional controls for monitoring the indicator system (single-circuit, dual-circuit control).
Marker lights (passenger vehicles) front
Number Two or four
Colours White, or amber when main headlamps are amber
Mounting The arrangement is the same as for the front direction indicators.
Miscellaneous Vehicles and trailers over 1600 mm wide require marker lights (to the front).

 

Tail lights
Number Two or four
Colour Red
Height position Between 350 mm and 1500 mm permissible
Width position Max. 400 mm from the outermost edge of the body. At least 600 mm apart
Electrical circuit No particular specifications
Miscellaneous In the event of dual function (stop and tail light), the luminous intensity ratio of the individual functions must be at least 5 to 1.
Rear fog lights
Number One or two
Colour Red
Height position Between 250 mm and 1000 mm permissible
Width position The distance to the stop light must be at least 100 mm.
Electrical circuit Rear fog lights may only work when low beam, high beam, or fog lamps are switched on. They must be able to be switched off independently of the fog lamps.
Switch-on control Amber, vehicles approved before 1981 also green
Miscellaneous The visible illuminated area must not be more than 140 cm2. The light may only be switched on when visibility is less than 50 m.
Rear fog lights
Number One or two
Colour Red
Height position Between 250 mm and 1000 mm permissible
Width position The distance to the stop light must be at least 100 mm.
Electrical circuit Rear fog lights may only work when low beam, high beam, or fog lamps are switched on. They must be able to be switched off independently of the fog lamps.
Switch-on control Amber, vehicles approved before 1981 also green
Miscellaneous The visible illuminated area must not be more than 140 cm2. The light may only be switched on when visibility is less than 50 m.
License plate lamps
Number Depending on requirements one or two lamps
Colour White
Mounting No particular specifications
Electrical circuit No particular specifications
Switch-on control Amber, vehicles approved before 1981 also green
Miscellaneous The rear license plate must be illuminated in such a way that it can be read at a distance of 25 m. The minimum luminance of the complete surface area must be at least 2.5 cd/m2.
Reversing lights
Number One or two
Colour White
Height position 250 to 1200 mm permitted
Width position No particular specifications
Electrical circuit The circuit only works with the ignition switched on and the reverse gear engaged.
Parking lights
Number Depending on requirements two at the front and two at the rear or one at each side
Colour White
Height position Between 350 mm and 1500 mm permissible
Width position Max. 400 mm from the outermost edge of the body. At least 600 mm apart
Electrical circuit The parking lights must be able to work without other lamps being switched on.
Switch-on control Amber, vehicles approved before 1981 also green
Miscellaneous The parking light function is usually taken over by the tail lights.
Side marker lights
Number Depending on the length of the vehicle
Colour Amber
Height position Between 250 mm and 1500 mm permissible
Width position Max. 3000 mm from the front edge of the vehicle and max. 1000 mm from the rear edge of the vehicle
Electrical circuit No particular specifications
Daytime running lights
Number Two at the front
Colour White
Height position Between 250 mm and 1500 mm permissible
Width position Max. 400 mm from the outermost edge of the body. At least 600 mm apart
Electrical circuit The daytime running lights must switch off automatically if the low-beam headlamps are switched on.

Installation regulations side view

Signal light regulations: Installation regulations side view

Side marker lights (SML) / Side marker reflex reflectors (SMR)
1 SML/SMR: Max. 1000 mm (from rear vehicle edge)
2 All: Max. 3000 mm
3 Direction indicator: Max. 1800 mm SML/SMR: Max. 3000 mm (from front vehicle edge)
4 SMR: Max. 900 mm, SML: 1500 mm
5 SML/SMR: Min. 250 mm
6 SMR/SML: Min. 250 mm, direction indicator: 350 mm
7 SMR: Max. 900 mm, SML/direction indicator: 1500 mm

Installation regulations rear view

Disposiciones acerca de los pilotos de señalización: Disposiciones de montaje - Vista lateral

Side marker lights (SML) / Side marker reflex reflectors (SMR)
1 Valid for direction indicator/stop light/tail light/reflex reflector: Max. 600 mm
2 Valid for direction indicator/tail light/reflex reflector
3 Centre high-mounted stop lamp: Min. 850 mm
4 Rear combination lamp: Min. 350 mm
5 Rear combination lamp: Max. 1500 mm
6 Centre high-mounted stop lamp: Max. 150 mm below rear combination lamp or 3

TYPE APPROVAL NUMBERS ON SIGNAL LIGHTS

National and international design and operating regulations apply for the manufacture and testing of vehicle lighting equipment. Special approval marks exist for signal lights and can be found on the light.

 

One example
The following can be found on a light RS1 IAF 02 E1 Æ 31483:

  • R stands for tail light,
  • S1 for stop light,
  • IA for reflex reflector,
  • F for rear fog light and 02 means that the regulation has been revised twice since publication.

 

These features are integrated in the rear combination lamp:

  • The E1 marking means that the light has been approved in Germany.
  • The arrow shows which way the light can be installed and therefore always points to the outer edge of the vehicle. If there is no arrow on the light it can be installed at the right or left rear side.
  • The five-digit number at the end is the type approval number.

HELP IN DECODING THE COMBINATIONS OF NUMBERS AND LETTERS ON SIGNAL LIGHTS

A Marker light
AR Reversing light
F Rear fog light
IA Reflex reflectors
R Tail light
S1 Stop light
1 Front direction indicator (different technical design)
1a Front direction indicator (different technical design)
1b Front direction indicator (different technical design)
2a Rear direction indicator
5 Additional side direction indicator (for vehicles up to 6 m in length)
6 Additional side direction indicator (for vehicles longer than 6 m)
SM1 Side marker light (for all vehicles)
SM2 Side marker light (for vehicles up to 6 m in length)

 

The permissible luminous intensity values vary depending on the function. Changes in movement (braking = 60 cd) have a stronger lighting signal than those for position and orientation (tail light = 4 cd).

 

S Tail light
B Stop light
ZB Additional stop light
BL Direction indicator light
ZR Tail light
NES Rear fog light
PO Position light