Pulling a Trailer With LED Lights and the Vehicle is Reading Lamps Out

Question:

Hello, Can you help me understand why a ballast resistor is required for each individual light on a trailer. More so why putting a single one on the return pin 3 earth on a 7 Pin plug wouldn’t work? I just need to trick the vehicle into thinking there is a lamp in the circuit so my thoughts would just solder a single load resistor on the 0v return pin and this would do all the lights. But I see you say I need 1 per circuit. Regards

asked by: Paul A

Expert Reply:

Though we do recommend having a resistor on each LED light, we do have other options as well.

Since you mentioned having a 7 Way connector, you could use a lamp out sensor adapter like the # 20142 if the trailer is wired with a 7 Way plug or a # C35FR if you have a 4 Flat or 5 Flat plug on the trailer. These have all the needed pieces to trick the vehicle's computers into working with LED lights on the trailer.

That being said, you could spice resistors into each of the wires attached to an LED light. It really wouldn't work just having one resistor on one wire as each function that has an LED can be read as having an open circuit with the new computers in vehicles.

expert reply by: Lazer S