Rear fog light icon in switch for VWs (euroswitch) (part 2)

If your circuit board is white or yellow in color and has no component markings on it then the task of doing this mod is a little bit more difficult. These steps apply to the circuit board whose traces look like the following:

     

  1. First we need to understand what the circuit looks like and what is missing. This is the schematic:

  2. Notice the Rextra in the following diagram, you have to remove that altogether.

  3. Then look for R1. This should already be there and should be around 1 Kohm.

  4. Add R3 and R4. R3 should be around 1 Kohm and R4 should be 10 Kohm.

  5. Add R2 in there. You can choose an appropriate value for R2 to get the right brightness for your rear fog light LED. Different color LEDs are rated at different voltages. 270 ohms should be the minimum value. Dont go any lower than that.

  6. Solder C1 in place. Its good to have this capacitor in place but you can live without it if you dont have one. A 10 nF cap should suffice.

  7. Add Q1 in place paying attention to the base, emitter and collector in there. Q1 is a generic PNP switching transistor.

  8. Solder your LED (D2) in place with the correct polarity. D1 is the red LED that should already be there.
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