Troubleshooting Running Lights on Trailer Not Working After Swapping to LED Lights
Question:
New LED lights on utility trailer. Turn signals work as well as brake lights, but not the running lights. Could I just put one resistor in-line up near the hitch that would work on both lights, or does each light need its own resistor?
asked by: Jim C
Expert Reply:
It is not necessary to install load resistors on a trailer that had it's bulb type swapped from incandescent to LED. Most likely you just need to ground the running light circuit or there is a short on it somewhere to cause it to not function properly.
First thing you should do at this point is test the 4-way of the wiring harness with a circuit tester part # PTW2993 for voltage on all of the right pins when the taillight signals are being applied. Just like in the video I attached.
If the voltage checks out there but the trailer lights still don't function right then the problem is on the trailer wiring. That would mean that problem is either due to a ground issue or a short issue.
Make sure that the trailer side connector are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces. The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.
If the problem is on the vehicle side then I would first recommend you double check how the harness is installed on your vehicle, make sure all of the connections are good and tight. You should check all towing related fuses and relays as well.
Products Referenced in This Question
Product Page this Question was Asked From
Sealed, 4" Round, LED Trailer Stop/Turn/Tail Light, 3-Function, 10 Diode - Red w/ Clear Lens
- Trailer Lights
- Tail Lights
- Stop/Turn/Tail
- Round
- Recessed Mount
- Submersible Lights
- LED Light
- 4 Inch Diameter
- Red
- Optronics
more information >
Continue Researching
- Q&A: Are Load Resistors Required when Adding LED Lights to a Trailer
- Q&A: What is the Difference in a Bias Ply and Radial Ply Trailer Tires
- Q&A: Difference Between ST205/75R14 and ST215/75R14 Goodyear Trailer Tires
- Q&A: Difference Between Trailer Tire Sizes ST205/75R15 and ST225/75R15
- Q&A: What is the Fuse Rating and Power Wire Gauge Used for Trailer Wiring Harness # 118571
- Article: Trailer Wiring Diagrams
- Q&A: Recommended Spare Tire Cover for 265/70R17 Size Tire
- Q&A: Comparing Tow Ready and Roadmaster Diode Wiring Kits for Flat Towing
- Article: How Harvest Hosts Is Becoming the New Standard of the Camping Industry
- Article: What are the Common Types of Propane Fittings Used on RVs?
- Article: Brake Controller Installation: Starting from Scratch
- Article: Wiring Trailer Lights with a 4-Way Plug (It's Easier Than You Think)
- Article: What Exactly is Tongue Weight?
- Article: Determining Trailer Tongue Weight