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Load resistors

9K views 8 replies 5 participants last post by  jizzlets 
#1 ·
I want to get led bulbs for my '13 wrx, especially the front and rear turn signals. But I'm reading that some cars needs a load resistor with purchase of these led lights or the lights won't work.

Does my car needs this load resistor? Or can I just install the led bulbs with no problems?

Tnx


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#2 ·
They should work but, without the resistor you will get what's called hyperflash. Hyperflash is when the turn signal or flashers go on and off very fast, just like when you have a bulb blown. They draw much less voltage than regular bulbs and that's exactly what the car thinks, the bulb is out. That's why they use resistors to trick it. Our forum vendor diode dynamics should be able to help you or explain better.

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#3 ·
Load resistors are typically wire wound - encased in an aluminum heatsink. Be sure to mount them to metal chassis because they can get HOT, ideally with a thin layer of thermo compound between the resistor and metal. It's not exactly good to mount them directly to a painted surface, but I've seen it done. I just don't recommend it. If you remove paint, be sure to protect it from rusting after mounting the resistor.
 
#4 ·
@jizzlets,

If you plug in some of the larger LED bulbs you will get a minor hyperflash. Its all a questions of resistance or in a closed system like a car wattage. For example the stock 1157A bulbs should be 27 watts and about 7 Ohms@14 volts. If you replace the bulb with another unit that also draws 27 watts you will have the same flasher speed. That said most LED units are very low resistance because of the way they choose to wire multiple LEDs. Depending on the particular LED bulb you choose if the resistance is high enough and it draws enough wattage then you will not get hyper-flash. In most cases LED bulbs are between 10 and 12 watts and they hyper-flash which is not good for your OEM flasher relay.

To resolve hyper-flash you don't necessarily need a load resistor. There are a few companies out there that make Flasher relays designed for LED indicators. If you look on iJDMTOY or SuperBrightLEDs and even on Amazon the LED specific relay can be had for as little as $10, then you dont need to modify your wiring harness or add additional resistance ( read heat ) to your engine compartment.

When you decide to order your new signals Google "8-Pin 81980-50030 066500-4650" Thats the part number for the LED ready flasher relay for our 13 Subarus.

**after-thought** I also have a 13 WRX, I went all LED for a bit as well. I picked up one of the super bright switchback LED turn signals ( the ones that go from white to amber ) and I was pretty displeased with the function. They are designed to be 5k white when your just driving and then switch to amber when the signal is on but they take one click of the relay before they switch. for me that meant that the front signals were not lit amber until the second tick of the relay. Im sure it would not be enough to cause any trouble but it made me hesitate when changing lanes or using the turn signal. So the front ones came out. Also the rear needs to be very bright, The LED towers ( looks like bee hives ) don't put out nearly enough light during daytime driving to replace your rear turn signals. The stock lamps are good for almost 400 munes so that should be your target when looking at LED replacement indicators Ive seen some as high as 550lumens but instead of spending the additional $20 per bulb I ended up using the stock bulbs for both.

If it would help I would be glad to PM you links for the LED units I have found to be more effective. as well as a link for that relay
 
#8 ·
- Less complicated yes, less interesting also yes.

There are quite a few LED bulbs that work but LED turn signals are not the inexpensive upgrade most folks are expecting. I have found bulbs that draw 20w using CREE LEDs. Output brightness is close to 25% brighter than stock but they go for about $25 per corner.

If you have any other questions about LED lighting please feel free to PM me
 
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