Depending on the LED ratings, you will need a current-limiting resistor in series with each LED, selected by R = (Vin - Vf)/If where R is the resistance you need, Vin is the DC input voltage, Vf is the forward voltage drop of the LED (should be specified in the datasheet) and If is the current required by the LED (also should be in the datasheet). A quick explanation of the resistors chosen: Assuming a nominal 12V supply, the 15Ohm resistor will allow a current of 0.8A. The power dissipated by the resistor will therefore = V*A = 12*0.8 = 9.6W, thus making the 10W rated resistor sufficient (particularly when installed with a means to transfer heat away). Usually the replacement type LED bulbs (many LEDs per bulb unit) are designed to divide the 12 volts across each of them to achieve the correct voltage on each individual LED (~ 1.9-3.6 volts usually). The bulbs have a couple rows of 3 or 4 LEDs in series (12v / 4 = 3 volts) bunched together. Not just any 330 Ω resistor will work for us, we need the resistor to meet or exceed the resulting power dissipation. Note: A resistor's power is rated in watts. The formula for electrical power is P (Watts) = I (Amperage) * V (Volts) In this case if you're changing 2x filament light bulbs you will need 2x load resistors). Video: Install a Load Resistor for LED Lights. Topics: Precautions: LED Resistor Wiring Diagrams: LED Load Resistors & LED Lights. LED Light Prices; Item: Location: Load Resistors: US Prices: AU Prices: UK Prices: CA Prices: IE Prices: FR Prices: LED Simple Blinking LED Circuit: A very simple circuit that you can build to blink or flash LEDs. The circuit is built using transistors, resistors, capacitors, and LEDs. Of course you will need a breadboard, wire jumpers, and a power source. The parts list includes: PNP… Without getting too technical, this simply means that the circuit experiences some additional current through the resistors when the LED signal comes on. So there you have it. Install one of these resistors into the circuit near your LED signal and you will increase the amount of current the OEM relay sees when the LED signal lights up WAuYBp.