The source of the backlight to the heater / fan sliders is from a 509T bulb located under the safety triangle. You could replace this bulb with a coloured LED 509T, but the LED head is much shorter than the filament bulb.

As such, the light is not effectively guided along the backlight channel. White 509T LEDs do emit more light, but they are still not ideal.

We have found that with a bit of patience and care, you can make an effective light source from two SMD PLCC-2 LEDs that you may have left over after replacing your LEDs in your triangle, radio and buttons.
In addition to two LEDs, you will need an appropriate resistor and two short pieces of wire. Most SMD LEDs draw 20mA but vary in voltage accross the LED. This will determine your resistor size. If you are unsure of what resistor you should use, then please contact us. Here are a list of possible options:

Take your components and arrange them as shown below.

Now very carefully, tin the ends of the wires with solder. You will need to be quick so as not to melt the insulation of the wire.

Now solder the components together ensuring that you get the LEDs the correct way around.

Bend the wires so that the LEDs face away from each other. Try not to apply any stress to the solder joints. You may wish to separate the backs of the LEDs with PVC tape, if you are worried about short circuits.

Take the triangle PCB and solder the leg of the resistor to the negative pad and the wire from the LED to the positive pad.

Carefully reassemble the triangle ensuring that the LEDs 'poke' out the hole in the bottom and don't get trapped. Angle the LEDs so that they will point along the route of the backlight channel.

Connect the triangle back to the car. Carefully push the triangle into place ensuring that the LEDs don't clash on the channel. Turn your side lights on to reveal a much improved slider backlight.