Relay Resistor Harness 101


Interface Solutions

Here at Race Sport Lighting we are commonly asked questions about interface solutions. What are they? Why do I need them? Well, we are going to be doing a five-part blog series breaking this topic down. Interface solutions are all about keeping the vehicle’s computer satisfied. Today’s vehicles are specifically programmed to interact with every aspect of the vehicle. Whether it be fuel and ignition timing or head lamp and tail lamp circuits.

What does this mean to you? Simple, when you remove and replace an item (like a bulb) and replace it with something that is not exactly the same, the vehicle will see this as a fault and respond with an error. The reason for this is that the replacement part is outside of the parameters the vehicle is programmed for. So to prevent error lights, flicker, or flashing. You have to use an interface part to compensate for the difference.

Relay Resistor Harness

The included load resistors provide necessary resistance & load to prevent “bulb out” errors, service vehicle lights, or pulsing. This applies to vehicles that have light circuits programmed to see specific resistance or current draw.
A relay resistor harness is commonly used in applications when these issues are present:
• On vehicles with bulb out errors, Lamp out errors, service vehicle lights, or repeated pulsing.

• On vehicles requiring resistance or current draw on a light circuit

• Used on most 2006 and Mopar vehicles

• Used on most 2006 European vehicles

Installing a Relay Resistor Harness

Be aware that one harness will do both left & right headlamps. The resistors are of a plug a plug and play type. Please be aware that resistors themselves must be properly secured to a flat metal surface with at least a half inch of clearance all around for heat dissipation. Please see this helpful diagram below for proper wiring of the harness.

Relay Resistor Harness

Race Sport Lighting Part # RELAY-RES