Troubleshooting Trailer Lamps That Receive Power But Won't Illuminate
Question:
I have installed a brand new trailer light kit. The connection to the car operates, there is power to both trailer lights, but the bulbs will not work. I have tested the ground and used a probe in the light sockets. both the turn signal pin and the tail light pin operated do the peanut bulb socket on the side but the bulbs will not light. I replaced all four bulbs with new ones and they dont work either.
asked by: R. M
Expert Reply:
If you're showing power on the black wire feeding the lamp, and the bulbs are known to be good, the only thing that could cause the lamp not to illuminate is a poor ground connection. You can test this theory by getting a long length of wire and attaching one end to the negative battery terminal of the tow vehicle and touching the other end to the ground wire of the lamp while the running lights are turned on. If the lamp lights, you've confirmed that there's an interruption in the ground circuit somewhere on the trailer. Make sure that the ground wire from the lamps is connected directly to the trailer brake, or a metal piece that's in contact with the trailer frame.
It's pretty unlikely that two lamps could be faulty. I'll link you to our trailer wiring troubleshooting FAQ article.
Product Page this Question was Asked From
Optronics LED Trailer Clearance and Side Marker Light w/ Reflex Reflector - 6 Diodes - Amber Lens
- Trailer Lights
- Clearance Lights
- Rear Clearance
- Side Marker
- Rectangle
- Surface Mount
- Non-Submersible Lights
- LED Light
- 4L x 1-1/2W Inch
- Amber
- Optronics
more information >
Featured Help Information
Miscellaneous Media
Continue Researching
- Video: Review of Demco Trailers - Replacement Fender Assembly - DM37FR
- Shop: ARB Base Platform Rack - Gutter Mount - 72" Long x 51" Wide
- Shop: Trailer Hitch
- Video: etrailer Class III Trailer Hitch Installation - 2021 Subaru Forester
- Shop: Replacement Fender Assembly for Demco Kar Kaddy 3 Tow Dolly - Passenger Side
- Shop: etrailer Trailer Hitch Receiver - Custom Fit - Matte Black Finish - Class III - 2"
- Shop: Roof Rack
- Q&A: Removing Trailer Bearing that is Stuck on Spindle After Removing Hub
- Shop: Replacement Fender Assembly for Demco Kar Kaddy SS Tow Dolly - Driver Side
- Shop: Replacement Fender Assembly for Demco Kar Kaddy X Tow Dolly - Driver Side
- Search Results: dm37fr
- Search Results: dm97fr
- Search Results: kar kaddy
- Shop: Replacement Fender Assembly for Demco Kar Kaddy X Tow Dolly - Passenger Side
- Shop: Replacement Fender Assembly for Demco Kar Kaddy 3 Tow Dolly - Driver Side
- Video: Review of Demco Tow Dolly - Replacement LED Fender Light - DM67VR
- Q&A: Trailer Lights Do Not Light Up But have Power on All Wires
- Shop: Suspension Enhancement
- Q&A: Troubleshooting LED Lights Not Working On Trailer
- Shop: Brake Controller
- Article: Trailer Wiring Diagrams
- Q&A: Should The Trailer Brake Circuit Have Continuity Between the Blue Power Wire and Ground?
- Q&A: Should There Be Continuity Between Running Lights And Ground Circuit While Bulb Is Disconnected
- Q&A: Adding an In Line Fuse to a 12 V Power Lead from a Vehicle Battery to a Trailer Connector
- Article: Troubleshooting 4 and 5-Way Wiring Installations
- Search Results: trailer hitch
- Shop: Trailer Wiring
- Video: Choosing the Right Trailer Wiring
- Q&A: What is the Difference Between a Class II and a Class III Hitch?
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
on Trailer Lights
