USDM lights on PreFaceLift A3 8V Halogen Headlight

   #1  

zabster

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Hi

Is it possible to activate Front Indicators to be On like DRL on PreFaceLift A3 8V with Halogen Headlight (SE/Sport) and to blink when indicating?

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PetrolDave

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Even if it's possible in the UK it would be an MOT fail as the MOT Guidelines now specify that front facing lights must only be white unless they are flashing indicators (so yellow front fog lamps are now an MOT failure).
 
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zabster

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Appreciate your reply but I am not concerned about MOT here I want to know if it can be programmed and if anything technically would not let that happen.
 
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DV52

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@zabster : arrhh........... yours is not the first time the question about so-called "US style DRLs" on MQB platform cars has been asked.
With @PetrolDave advice about the legal ramifications of such a tweak in your country acknowledged- there is also an engineering consideration.

I'm not sure how the Halogen headlights are configured on your car - but I suspect there's a high probability that the turn-signal lamps are also halogen. If this is the case, then on other MQB platform cars (especially the Golf mk7), this tweak caused the lamp holders on the turn-signal bulbs to overheat and some actually melted!

Again with the caveat that I'm not sure about Audi A3 8V equipment, the reason for the problem on Golf mk7s was that the turn-signal lamp base is only rated for the 50% duty cycle that happens when the blinker operates (i.e. the turn-signal is OFF for 50% of the time that the blinker is activated). This means that the lamp base doesn't need to be fully rated for 100% switch-ON - and of course, VAG captured the resulting cost saving on their production line by de-rating the fitting equipment!!

I don't know how engineering minded you are - but when the lighting function for a lamp is changed from turn-signal to DRL mode, there is an effective doubling of electrical current in the lamp. Now, when the current is doubled, the laws of electricity stipulate that the power that is dissipated by the lamp is quadrupled. This means that for DRL operation, the lamp base must carry 4 x times more power than it's designed rating!! This is a not-trivial additional impost on the turn-signal lamp base!!

Something to consider - if you proceed with the tweak, I suggest that you decrease the illumination level of the DRL function to no more than 50%. Alas I suspect that the necessary consequence of this need for lower DRL illumination will make the lamp virtually un-seeable during daylight. So I suggest that you think about whether it's a worth-while change to make at all (your decision- of course)

Don
 
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   #5  

zabster

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@DV52 thanks a lot. The reason I asked was because I had seen someone selling adapters to set USDM on A3 8V with Halogen headlights and I could not understand why just coding won't do the job.
I have read of Golf having the issue with bulbs you have mentioned but again I don't see how adapters can make it any better for the bulbs. I assume if bulb is an issue then bulb could be changed.
Anyway thanks for your reply.
I currently have aftermarket LED headlights but when I get chance I am going to test USDM with dimmerwert below 50% on OEM Halogen headlight.
 
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