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      10-09-2012, 07:24 AM   #8
chx437
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Drives: BMW X3(G01)
Join Date: Jun 2011
Location: Finland

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Here are some hints on the LED turning signal lights and brake lights for the X3(F25). My experience is from Europe but I suppose the rear lights are quite similar in US model. The product example links below direct to a good German web store specialized for LED bulbs but the same LED products are hopefully available from other sources as well.

Rear turning signal:

So the rear turning signal (blinker) bulb is originally clear PY21W (21W normal incandescent lamp) with BA15S base. There is a rather strong amber filter (diffusor) in front of the bulb, so the replacing LED bulb has to be quite effcient. My alternative for the rear blinker bulb is here: amber colored 9W LED for BA15S base with 5 watt CREE on the tip and 4 times 1 W LEDs on the sides:

http://www.benzinfabrik.de/de/led-bl...s-p21w-orange/



Front turning signal:

In front at least in the European model the turning signal bulb is originally amber PY21W (also 21W incandescent lamp) with BAU15S base. Note that the base for the clear and the amber PY21W bulbs are different: for the amber bulb the base has asymmetric positions for the small nodules on the sides. My alternative here is amber colored 9W LED for BAU15S base with 5 watt CREE on the tip and 4 times 1 W LEDs on the sides:

http://www.benzinfabrik.de/de/led-bl...-py21w-orange/


Parallel resistors needed for LED blinker bulbs:

With the blinker bulbs my X3(F25) has very strict in-built control: the bulb has to pass through at last 1.5 – 1.6 A current to be validated Ok by the car control computer. If the current is less, then an error message is shown on the display (and the blinker on/off cycle time gets faster). So with the LED blinker bulbs, which use less current, I have to add parallel power resistors (10 ohms/25W, one for each LED bulb) to keep the control computer happy. I couldn’t place these relatively big resistors into the rear light housing but instead I placed them on the sides in the trunk. I first have to dig out the cabling in the trunk sides going towards the rear light housing and especially toward the blinker bulbs and then connecting the resistors parallel to those wires. I fastened the resistors into small aluminum plates (for cooling) and then I installed the plates (with the resistor) into the trunk sides (under the side covers), where there actually were plenty of room for these small additions.

In front the turning signal bulb is installed on a small “disc” which can be removed as one peace with the bulb from the back of the headlight housing (inside the motor room). There is no place either in the headlight housing for the needed parallel resistors so I had to get wires through those small plastic discs and then I installed the power resistors (fixed into cooling plates) on the sides of the engine room.


Brake light:

The original brake light bulb is again a clear P21W with BA15S base. My LED alternative for that is a red LED bulb with 4 LEDs (1 W each):

http://www.benzinfabrik.de/de/led-fu...a15s-p21w-rot/

Brake lights bulbs are easier to install: at least in my car the control system was gentler for the brake bulbs and no additional resistors were needed when using the LEDs


One additional note:

The above referred LEDs are not accepted in the in the official vehicle inspections (at least not in most European countries) so one has to take this into consideration when planning such modifications.
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