Tag Archives: light

Upgrading the number plate lights to LED on the Volkswagen Golf, Jetta, GTI, R32, Rabbit and Passat


The bulb indicator denotes a failed bulb
The bulb indicator denotes a failed bulb


The rear number plate lights can be upgraded to LED however there is a problem with the bulb monitoring detecting failed bulbs and displaying a warning on the instrument cluster and MFD. There are a few approaches that can be taken and all revolve around adding extra resistance to the rear number plate light circuit to prevent the warning, one option is to install a resistor inside the car on that citcuit and the other approach is to add the resistor to the LED lights whilst being mindful that the bulbs are enclosed in a sealed enclosure so excess heat will melt the light fitting (as will fitting 10watt bulbs like the Polargs to replace the existing 5 watt bulbs).

The point at which the bulb out warning activates is around 6 watts and the LED modules that were used here are 1.5 watts so an additional 3 watts of load was required, after some testing 2 x 270 ohm resistors performed nicely and did not generate excessive heat.

Parts required are

Start by wrapping the resistor around the body paying attention to the end that is isolated from the body (some shrink wrap will be placed around this end to prevent a short circuit), once the legs are fully wrapped use a dremel/sandpaper/file/knife to scratch away the coating near the legs in preperation for soldering. Place some shrink wrap over the resistor and the leg on the end that is isolated and solder the legs to the end caps.

The resistor needs to be kept close to the body to maintain clearance to fit into the housing and to transfer heat to the body away from the resistor.


Once both units have been finished all that’s left is to fit them, these are polarity sensitive so if they don’t work the first time you put them in reverse them. When fitted to the holder correctly as shown below they have room to spare on each side. Make sure they are facing downwards as the light output is very directional unlike the standard bulb which outputs in all directions.


Volkswagen Golf Emergency Brake Warning Flash

When braking in an emergency the hazard lights flash to warn traffic following behind.

This feature can be turned on and off in Vagcom/VCDS using Byte 17 Bit 0.

For the lights to flash the following parameters must be met

  • Deaceleration has to be higher then 7m/s² and
  • for a duration longer then 700ms or
  • the ABS must be active for more then 2 seconds.

Once one or both of these requirements are met the indicator lights will flash until until the paramters are no longer met.

Volkswagen Golf Reverse Light Upgrade PIAA XTREME

PIAA 27watt XTREME Globes
PIAA 27watt XTREME Globes

The PIAA XTREME White Bulbs that I ordered a few weeks ago arrived today, going by the reviews and the claim this should not only give me a whiter light but extra light out the back. Whilst the coating on the globe would reduce light output to a certain extent the fact that they were 27watts instead of the standard 21watts instilled me with confidence that they would achieve both of these claims and resolve one of the minor issues with the VW Golf GTI which is only one reverse light.

They arrived well packaged in a nice presentation box and I fired up the lux meter in preparation for a blinding display from the PIAA. The results speak for themselves.

Measured on a digital lux meter at 500mm and 1100mm.

Standard 21watt          PIAA 27watt
403                             146   (550mm)
75                               27   (1100mm)

Pretty disappointing and whilst the light from the PIAA looks whiter and brighter when looking at the globe it doesn’t illuminate anywhere near the same area as the standard globe. Needless to say the PIAA globe has been removed. The globe also felt a fair bit hotter (hotter then expected) then the standard 21watt globe, the coating also smelt burnt (may have been because the coating was new). Needless to say the globe has been returned to standard.