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2018 Mazda3 Touring, 2.5l, 6-speed manual
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Discussion Starter · #1 ·
It never occurred to me that by swapping out my stock headlight bulbs for LEDs (Torchbeam T2 9005/HB3 H11/H8 LED Headlight Bulb Kit) that I'd lose my DRLs, which apparently happened. I had them installed at my dealership and no one said anything about potential consequences of the swap (if, in fact, the swap's what did it). I tried the brake pedal-parking light-flashers-parking lights procedure to no avail - and I'm pretty sure I did it in the 23 seconds allotted. Any help?
 

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First, the obvious required questions - you are replacing halogens with LEDs, right? You checked for DRL operation with the parking brake disengaged?
If so and the DRLs aren't working, the dealer is clueless about LED swaps. You need to install a small adapter harness with a resistor to make the DRLs work.
You need to have the high beams wired in this configuration, with both bulbs powered from the passenger side plug and the resistor attached to the drivers side plug.



This harness is required to make it work -
Lots of threads here on LED conversions, plenty of information available.
This video was made by a member here a while back.
 

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Dude! Thanks so much for that - I'm a certified mechanical/electrical idiot, and it makes sense to me! Now to speak with the dealership. Many thanks again!
Its all about providing the right resistance in the circuit and tricking the ECU into thinking that there are halogen bulbs in the sockets. Without the extra parts, you get either no DRLs or just one on the passenger side.
The dealership probably won't be of much help.....they would have to install aftermarket parts and modify the electrical system and most won't do that even though its a very simple procedure.
 
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