LED Inserts for indicators and Rear- / Brakelight (last edit: 25.10.2010)

I guess it is a thing of personal preference if you would use traditional bulbs or modern LEDs. Well ... I´m an enthusiast for LED technology for many years. In modern cars you won´t find any bulbs for indicators and brakelights either, and high power LEDs are now available everywhere easily for an affordable price.
I decided to use Luxeon Emitter ones, which operate at 350mA, or 1W each LED.
Three of those LEDs equal the amount of light delivered by a 21W bulb, however they emit the light much more towards one direction, but I don´t see a disadvantage in this use case.

So here we start. Removing the lamp from the chassis is relatively easy, so I will not cover that...:
It is always a good idea to clean the lamp from dust and dirt before proceeding.

Here I already removed the the bulb. In the front you can see the PCB with the LEDs

The PCB is designed to fit easily into the lamp without any modification. So gently push it in and turn it 90° with the LEDs facing forward.

Now we need to fix the PCB inside the lamp. Use a bit of hot glue. Take care to position the PCB exactly at the place inside the lamp neck where the reflector starts. You will need the space between PCB and the bulbs socket later for storing the wires.

Now cut the wires to the desired length an run them through one of the holes which are at the side of the lamp socket. The black wire is ground and has to be connected to the side contact (at the 12 o Clock position on the pic) The red wire is the brake light, the gray one the rear light. Both are using the same (red) LEDs, but the current is different. While the rear light only uses about 20mA, the brake light gets the full 350mA allowed for the LEDs. Well, in fact I decided to use about only 340mA. This saves the LED and doesn´t affect brightness.

Last step is to route the wires in a way they don´t block the way for the bulb socket when latching it back into the lamp

That´s it! Enjoy! .... ehh wait! There is something more to mention....

Of course those tiny PCBs can not only be used for the rear and brake light, but also for the indicators. You only have to omit all components which are not used in this case, and to use amber colored LEDs instead of red ones.
However, when using those LED lights for the indicators, it causes another problem to appear: the indicator relay. This is designed to report the failure of a bulb by doubling the flashing frequency. As the current of the LED insert draws much less current compared to an ordinary bulb (350mA vs. 1,7A) , the relay will think the bulb is defect.
I think the easiest and most elegant way to overcome this problem is to replace the resistor inside the relay, which is measuring the current. Here are two pictures of the mod:
The current through the indicators is measured across the wire shackle in the upper picture. This needs to be replaced by a resistor, which takes into account the lower current through the LEDs.
The upper picture shows the original relay, the lower one the modified with the mentioned resistor (0,1 Ohm / 5W). This value is correct for two standard indicators and two LED indicators. In case you would like to replace all 4 indicators with LEDs, you need to use a 0,15 Ohm resistor. I already confirmed this to work excellent when 4 LED inserts are installed in the car.