What is a resistor and why would I need one?
Purposes of a HID resistor...
The first purpose the resistor can serve is to act as a dummy for your stock halogen bulb. Your vehicle sends a signal from it's computer system to your headlights in order for them to function. Some vehicles encounter problems when the vehicle sends the signal and it does not see the stock halogen bulb and therefore malfunctions in some way. Symptoms can include false headlight bulb out message on the dash, malfunctioning of other gauges on the dash and other various problems. The resistor is the same wattage and ohms as your stock halogen bulb. What happens is your vehicle sends the signal to the headlights and hits the resistor first which mimics your stock halogen bulb. When the vehicle system sees the resistor it sees it as the stock halogen bulb and reports properly back the system allowing everything to function properly.
The second function of the resistor is the handle vehicles with overpowering issues. Most commonly diesel trucks but can also include Dodge, Jeep, Chrysler and some Ford trucks as well as a few others. The need for a resistor can vary between vehicle models. The resistor will only allow the proper voltage to your kit which ensures its functionality. In most cases the symptoms will be flickering, pulsing lights and lights cutting out completely, or just complete cut out.
The third function of the resistor is specific to a Bi-Xenon application. In some cases after installing a Bi-Xenon kit either your Low beam will not come on or it will not switch from the Low beam to the high beam. When this happens a resistor is needed on either the high beam or the low beam depending on which one is causing the issue. In this case the resistor must be spliced into either the low beam or high beam wire on the RELAY SIDE NOT YOUR VEHICLES FACTORY HARNESS.