Retrofitting the speedometer with LED: Manual Guide

Retrofitting the speedometer with LED: Manual Guide

A defect occurring in older cars is only noticed after a time as it occurs gradually: your speedometer lighting getting weaker and weaker. This is caused by filament lamps, which still can be found in car dashboards. The proper solution is offered by a light source on its way to replace the traditional light bulbs: LED.

What are the LEDs?

what are ledsLED is the abbreviation for Light Emitting Diode, an electronic component used for generating light. In many ways, it is different from filament lamps.

The diode is a so-called semi-conductor, which means it conducts current in only one direction. Generally, this is irrelevant for the replacement of filament lamps with LED.

The replacement lighting has been correctly polarised in the factory. If you prefer adaptation of the instrument cluster lighting with the help of a soldering iron, you must mind the markings. Both LEDs and the circuit board are always explicitly marked. How to correctly identify the polarity and prevent errors when soldering will be explained later.

Advantages of LEDs

LEDs have many considerable advantages to filament lamps, such as:

– extended durability
– less heat development
– brighter lighting
– additional comfort

On condition of choosing a decent quality when installing LEDs, they are apt to last a car’s life span – and beyond that. Therefore it could be worthwhile to de-install replaced LEDs from speedometer and signaling when scrapping a car. These can be used in the next car without any problem.
led power consumption

  • LEDs consume considerably less power than filament lamps.
  • They transform more energy into light and generate less heat. This can only be an advantage in the narrow space behind the dashboard instrument panel.
  • LEDs shine significantly brighter and more powerful than filament lamps were able to do without producing a heat build-up.

Not only can LEDs be dimmed at your convenience.

  • Its last generation, the RGB LEDs offer interesting light effects.
  • RGB is short for Red Green Blue, the basic colours able to generate any light colour.
  • An RGB LED can be adjusted to your favourite colour or illuminate the speedometer with an exciting light show.

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LED conversion for beginners

LED conversion for beginnersConverting a speedometer from filament light bulbs to LEDs is quite easy. All you need:

– a de-installation manual for the instrument cluster
– proper tools
– approved lamps
– patience and steady hands

how to remove the dashboard cluster1. The filament lamps are mounted at the back of the instrument cluster with turning connectors. To reach them the instrument cluster has to be removed.

  • Depending on the type of car this can be a tricky job. By all means, try to remove the instrument panel without removing the steering wheel.
  • The airbag is integrated into the steering wheel. To remove it requires technical expertise.

speedometer plexiglass cover2. When removing the instrument panel, beware of two things. The plexiglass cover is rather delicate and can break easily. An awkward twist of the cluster is often enough to cause a breach. Unfortunately, the cover is not available in a separate spare part. The only option now is visiting the scrapyard or searching for private ads to obtain the fitting replacement.
the speedometer disc coating3. The windowpane should not be removed when replacing filament lamps with LEDs.

  • If it is damaged or happens to fall out, do not touch the fittings with your bare hands.
  • The matt black layer does not agree with the sweat of your hand palms.
  • The stains do not come off. The replacement LEDs are also offered as retrofit LEDs, meaning that they are already adapted to the available fittings.

Therefore the following procedure is recommended:

1. Remove the speedometer in one piece.
2. Work on the speedometer in a clean working place, e.g. a desk.
3. Wear cotton gloves when working on the speedometer.

When the speedometer is de-installed, the filament lamps are removed with needle-nose pliers. The protruding socket is clamped and twisted 90°. Then it can be pulled out.

The LEDs are now installed in the reverse order of steps, the speedometer is re-installed – ready.

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Conversion of LEDs

Nowadays, many cars are fitted with LED lights on the speedometer ex-works.

For reasons of the economy, several manufacturers use lamps of mediocre quality. It can, therefore, happen that supposedly durable LEDs untimely lose their brightness or fail completely.

Replacing these is somewhat more complicated and should be thoroughly practiced in advance.

There are two ways of converting the speedometer:

– Replacement of the soldered components.
– Conversion to LED strips.

replacement of the firmly soldered LEDs on the speedometerThe replacement of soldered LEDs certainly is the correct and safe way, provided sufficient expertise is available. If you indiscriminately attack the instrument panel with a soldering iron, you are likely to cause greater damage. The most important thing when soldering LEDs is observing the polarity.

Installation of the speedometerTo say it in advance: although a faulty polarity will not cause a cable fire, the diode will simply not function. If you fail to notice this until after re-installing the speedometer, all the work has been in vain.

Determining LED polarity

Determining LED polarityFor dashboard illumination, exclusively SMD-LEDs are used.

  • SMD stands for a surface-mounted device, i.e. the component is soldered directly onto the circuit board surface.

The traditional construction of many electronic components has pins to be inserted into the holes in the circuit board and soldered on the backside. This construction is very complicated and particularly unsuitable for automated assembly, though all the more for manual assembly. For DIY purposes, LEDs with pins are still available.

The polarity is determined by the length of the pins:

  • The longer one is the anode or positive pole
  • The shorter one the cathode or the negative pole.
  • Their position is indicated on the circuit board by + or -, or alternatively with “A” or “C”.
  • The pins are cut off after soldering and the used Pin-LEDs can therefore not be used again.
  1. Unsoldering SMDs is rather simple. Using two soldering irons is the better option. The SMD is heated on both poles and put aside after a few seconds.
  2. Soldering is more complicated. Still, the polarity marking of the SMDs is very obvious: SMDs always come with a missing corner.

This missing corner is indicated on the circuit board with a symbol. The SMD is installed in the turning direction showing the missing corner completing the symbol.

Retrofitting all SMDs on a speedometer originally equipped with LEDs will take several hours. The conditions are the proper tools, a steady hand, ideal working conditions and plenty of experience. There is an alternative, which involves some tinkering, though can lead to a satisfying result.

LED conversion with light strips

LEDs, particularly RGB LEDs are also available as so-called light strips with SMDs soldered onto them. These trips can be cut through anywhere. Many DIY tuners organise their conversion to LED as follows:

– Remove the instrument panel.
– Remove the window pane from the instrument.
– Glue the LED strip on the edge.
– Connect the LED strip to the dashboard circuitry.
– Re-install everything.

remove the disc from the dashboard cluster

  • The windowpane must be removed from the instrument panel and therefore you should wear cotton gloves.
  • The instrument cluster is now fitted with a surrounding, indirect illumination. This solution is suitable for an exciting illumination of rpm gauge, clock, speedometer, engine temperate gauge, and all other manual instruments.
  • This solution is not equipped to control signals, engine lights check, engine temperature, battery current, ABS and airbag lights.
  • Here you depend on the traditional lights.

Foto: Denis Dryashkin, Alexandru Nika, Den81, Dmitri Ma, Leonardo da, Aleksandr Kondratov, algre, RookieShutter, Ivaschenko Roman, Syda Productions / shutterstock.com

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