A lot of automakers such as Acura/Honda, Lexus/Toyota/Scion, Dodge/Chrysler, Mazda, and Subaru choose to use the high beam function as daytime running lights, meaning that the same high beam bulb lights up dimly during the day as it only receives about a 6-9V input. This configuration causes the daytime running light to light up with a dull yellow color that many people opt to go for the LED route. However, replacing your daytime running lights with just an LED bulb isn't as cut and dry as it appears. Most of the time, the LED bulb doesn't receive enough power and will give you a whole slew of issues like throwing a warning message on the dashboard, flickering, partially light up or even not lit at all.
Fortunately, that can be fixed with one of several R-setups for LED daytime running lights that include special decoders that are designed for specific vehicles in the Toyota, Lexus, Honda, or Acura line. While the R-setup configurations are plug-and-play, you will first need to determine which setup you will need, if you even need it at all. To see which R-setup your vehicle needs, follow this step-by-step troubleshooting guide based on the symptoms you see.
Step 1: Honda and Acura
Do you have a Honda or Acura?
After you install the LED bulbs, they both light up. However, there is a warning message on your dashboard.
You will need an R2 setup that includes resistor DRL decoders. The resistors and harness in the R2 configuration will eliminate the warning message on your dashboard.
Step 2: Newer Model Lexus or Toyota
Do you have a newer model Lexus or Toyota?
1.) The LEDs light up intermittently or flicker in the DRL mode.
2.) Both LEDs light up full power when the high beam is on.
You will need an R4 setup that includes DRL canceller with capacitors. The capacitor of the R4 decoder will help stabilize the current oscillation. Connect the decoders included in the R4 configuration to the positive wire of your stock harness to eliminate any flickering.
Use an LED tester to determine which side of the stock socket is positive and negative before you plug in the R4 decoder box. The R4 decoder is polar sensitive!
Step 3: Older Model Lexus or Toyota
Do you have an older model Lexus or Toyota?
1.) When one side of the vehicle has the LED bulb installed, the LED bulb will light up but the stock halogen bulb will not.
2.) When LED bulbs are installed on both sides, neither of them light up or only a portion of the bulbs light up.
3.) Both LEDs light up full power when the high beam is on.
You will need an R1 setup with DRL decoders. Connect the load resistor special decoder and special 3-in-1 harness in the R1 configuration after you remove the stock bulbs from the socket. This will ensure that the LED bulbs light up without any malfunction.
What if your LED bulbs don't flicker and don't display a bulb-out warning message on the dashboard?
If you're really lucky, cars like the Scion FR-S or the Dodge Charger don't require any decoders at all! Simply install the new LED daytime running light bulbs and you're on your way to a whole new look.
As you can see, converting your high beam DRL to LED daytime running lights doesn't have to be a frustrating experience. As long as you follow the appropriate symptoms and diagnostics, you'll be well on your way to a nice "HID matching" look for your car.