Step by Step
- Using a battery or jump box, connect one end of the black test lead to the negative terminal & the other end to the “Ground” pin. ...
- Connect the second test lead to the positive terminal of the battery or jump box. ...
- Make contact with the alligator clip to the “Left Turn/Stop” pin. ...
- Touch the alligator clip to the “Running Lights” pin. ...
Full Answer
What should I do if my trailer lights are not working?
So check the lights. If the bulbs are not the problem, disconnect the trailer's wiring system from the tow vehicle. Test all of the lights, from the backup lights to the turn signals and brake lights to ensure the problem is not the tow vehicle itself.
How to test trailer lights wiring?
Let's take a look at how to test trailer lights. The best way to solve your trailer lights wiring issue is to eliminate possible problems one-by-one until you have pinpointed the root cause of the malfunction. It is possible that one of the bulbs on your trailer burned out. So check the lights.
How do you troubleshoot a tow tail light?
Tail light housings should be secured to a metal surface (trailer frame), not wood or plastic. Use a circuit tester to check whether current is flowing through. The cause for only some of lighting functions working may also lie in “hot” wire issues. Use the circuit tester to see if current is going to the light fixture itself.
Why do my trailer lights go in and back on?
If the output is going in and back on the right wires, the reason may be wrong trailer wiring, including improper ground wire connection, dirt or rust buildup, pinched or cut harnesses. Troubleshooting trailer lights can appear to be intricate, but a good visual inspection can take a great deal of problems off.
What would cause trailer lights not to work?
Many trailer problems are due to a poor grounding connection, which is usually the white wire coming out of the trailer plug. If the ground is poor, lights may work intermittently or not at all. Even if the wiring to the plug is adequate, make sure that the ground connections to the trailer frame are good.
Why do all my trailer lights work except running lights?
If there is no signal on the wire here, then it is likely the wire is damaged somewhere along the trailer. Try tracing the wire as much as possible from the junction box to the taillights. If you are able to find the damage, replacing the damaged section of wire will complete your trailer's running light circuit again.
How do I fix my trailer light wires?
2:527:34How To Repair or Replace 4-Wire Flat Trailer Wiring Connector HarnessYouTubeStart of suggested clipEnd of suggested clipYou want to slide it down far enough that the heat from the soldering is not going to cause these toMoreYou want to slide it down far enough that the heat from the soldering is not going to cause these to start to shrink. So make sure you separate your wires enough that there's plenty of room for that.
Is there a fuse for trailer running lights?
The trailer running light fuse according to your owners manual is F29 and is a 20 amp blue fuse. You will also want to check the trailer tow receptacle fuse F30 which is a 30 amp pink fuse.
Why do my brake lights work but not my running lights on my trailer?
Expert Reply: It could be a tow package fuse on the vehicle. Use the owners manual to find the locations of fuses/relays related to the tow package wiring to check them and replace as needed. If the issue is not a fuse or relay then you can test the vehicle side trailer connector using a circuit tester such as # 40376.
Why are my brake lights not working but my tail lights are?
The most common reason your brake lights are not working but tail lights do is a bad light bulb. It can also be caused by a blown fuse, bad brake light switch, or issues with the wirings. Your vehicle's taillights are working fine, but the brake lights don't come on when you press the brakes.
What color wires go together for trailer lights?
Trailer Wiring Has 5-Wires White, Yellow, Green, Yellow/Brown, and Green/Brown On a 4-Way flat trailer wiring harness, white is the ground, brown is running lights, yellow is left turn signal and green is right turn signal. It sounds like your trailer has a wishbone harness.
How do you splice light wires on a trailer?
2:336:38Dog Chewed the Trailer Wires - Splicing on New Plug - YouTubeYouTubeStart of suggested clipEnd of suggested clipPut your wires in crimp both ends. And then heat shrink it.MorePut your wires in crimp both ends. And then heat shrink it.
How do you fix a broken trailer wire?
0:2817:10Repair broken trailer wiring cable. - YouTubeYouTubeStart of suggested clipEnd of suggested clipBack the insulation some to expose these inner wires. And starting to make the repair. First step isMoreBack the insulation some to expose these inner wires. And starting to make the repair. First step is cutting off the bad. Part.
Why are my running lights not working?
If Both DRL Are Not Working, Check the Fuse Check the fuse if both daytime running lights are not working. If the fuse is blown, there is likely another condition with the electrical circuit, like bad sockets or a wiring issue. The ambient sensor could also be disconnected or faulty.
Where is the trailer fuse located?
0:241:33TRAILER TOW PACKAGE FUSE LOCATION (2008 - 2016) - YouTubeYouTubeStart of suggested clipEnd of suggested clipThe main fuse box is located under the front hood just next to the vehicle battery.MoreThe main fuse box is located under the front hood just next to the vehicle battery.
How do you check running lights on a trailer?
Press the brake, hazard lights, and both blinker lights while someone stands behind the trailer to see if all the lights are working properly. The lights on the trailer should correspond with the lights on the back of the tow vehicle. If some lights don't turn on or are dim, take note of which ones are malfunctioning.
Why are my running lights not working?
If Both DRL Are Not Working, Check the Fuse Check the fuse if both daytime running lights are not working. If the fuse is blown, there is likely another condition with the electrical circuit, like bad sockets or a wiring issue. The ambient sensor could also be disconnected or faulty.
How do you test a ground wire on a trailer?
1:242:57Trailer Wiring Diagnosis: Bad Vehicle Ground - YouTubeYouTubeStart of suggested clipEnd of suggested clipOn our trailer wiring and we're gonna connect our ground on our circuit tester to our grounding postMoreOn our trailer wiring and we're gonna connect our ground on our circuit tester to our grounding post on our four flat connector.
How do you troubleshoot a 7 pin trailer wiring?
1:473:037-Way Trailer Wiring Review and Testing - YouTubeYouTubeStart of suggested clipEnd of suggested clipNow to test the functions while it's installed on a vehicle the easiest way is to use a circuitMoreNow to test the functions while it's installed on a vehicle the easiest way is to use a circuit tester we're going to start by grounding it to the frame of our vehicle.
Why are my rear lights not working?
The most likely cause for malfunctioning tail lights is a blown fuse, followed by a problem with the wiring or the control switch. Other causes include bad light bulbs, faulty bulb socket, or a bad light sensor. The taillights have separate controls, wiring, and sockets for each of the functionalities.
What to do if your trailer lights are out?
If the bulbs are not the problem, disconnect the trailer's wiring system from the tow vehicle. Test all of the lights, from the backup lights to the turn signals and brake lights to ensure the problem is not the tow vehicle itself.
How to check if trailer lights work?
Disconnect the trailer from the vehicle and run a test to determine if the trailer lights function properly. Wire the vehicle side wiring harness to a standalone battery. All you have to do is link up the white wire to the negative and the colored wires to the positive. If the trailer lights function with such a setup, it is clear the issue is with the tow vehicle.
How to check trailer wiring?
If the vehicle's lighting system functions as designed, grab a trailer wiring tester to check the tow vehicle socket. However, the tester must fit the tow vehicle socket. It might be necessary to use an attachment to properly test the system. Plug in the tester to the socket. Check the indicator (s) to determine if there is an electric current. There should be an indicator for each individual function. If the tester responds to each individual system, the trailer wiring system is probably the cause of the problem. If one or several test results do not provide a response from the tester, the tow vehicle itself might be the problem. If the tester illuminates when it should not (example: a phantom turn signal illuminating), it is a sign there might be a short in the tow vehicle wiring. Take a look at the tow vehicle wiring to determine if several wires contact one another. It also might be possible that several wires are connected to improper connection points. If this is the case, use wire cutters, a crimper and a wire stripper to perform a swap. Be sure to check out our trailer wiring diagrams for wiring identification and how to wire a trailer for additional information.
Why is my trailer light flickering?
Ground problems are the top cause of issues with trailer wiring. Begin by cleaning the ground connections. Each component should have its own ground to the frame of the trailer. If the trailer lights flicker on and off, there is a good chance the trailer is grounding by way of the hitch instead of through the trailer's wiring connector.
How to fix blown fuses on trailer?
Check the fuse on the powered converter to ensure it is still functional. Take a look at the tow vehicle lighting fuses. Examine the wiring on the trailer side and vehicle side for in-line fuses. If the blown fuses continue, it might be the result of the circuit being overloaded. One solution is to replace the trailer lights with LEDs.
Why are trailer lights important?
Your trailer's lights are essential to safe operation. Oftentimes, these lights prove problematic in the warmer months when the trailer is used at a high frequency after sitting idle for the winter.
Should wiring be cleaned?
It is worth repeating: the wiring should have secure and clean grounds at all times. If the grounds are compromised, perform a thorough cleaning and it just might do the trick.
Why is my trailer light going in and back on the wires?
If the output is going in and back on the right wires, the reason may be wrong trailer wiring, including improper ground wire connection, dirt or rust buildup, pinched or cut harnesses. Troubleshooting trailer lights can appear to be intricate, but a good visual inspection can take a great deal of problems off.
Why are my trailer lights not working?
Because the most common reason for trailer lights not working properly is a bad or missing ground, check the trailer’s and truck’s ground connection first. A poor ground often becomes the culprit when only some lighting functions are working and when lights go out when you push the brake pedal.
How to avoid false ground from tow vehicle to trailer?
To avoid false ground from the tow vehicle to the trailer, make sure that the trailer hitch and the tow vehicle ball, as well as safety chains or cables are disconnected. Jack and plug should be the only connection between a truck or SUV and a trailer. Submit your review. Name:
Grounding
- Before you dive into testing & fixing trailer lights, understand how important grounding is to trailer lighting. It doesn’t matter whether your trailer has LED (Light Emitting Diode) lighting or filament bulbs, they both need a good ground to illuminate. A light fixture may use the metal part of the frame to serve as the ground, or a more common (& better) way is to run a separate ground wire …
Testing The Truck / Vehicle
- Tools Required:Use the Circuit Light Tester& Alligator Clip Test Leads. Helpful Documents:It would be helpful to print out the wiring diagram for the vehicle end receptacle to look at while you are testing to assure that you are testing the correct pin. Assistant (Recommended):You will need someone in the vehicle to help you with this portion of the test. Step by Step Instructions 1. Wire…
Testing The Truck
- Tools Required:Use a Truck Trailer Plug Tester with LED Display. This tester plugs into the receptacle and has an LED light indicator for each of the pins. Assistant (Recommended):You will need someone in the vehicle to help you with this portion of the test. 1. Plug the tester into the truck’s receptacle. 2. Have an assistant complete each of the ...
Testing The Trailer
- Tools Required:Battery or Jump Box & Alligator Clip Test Leads. Assistant (Recommended):You will need an assistant to view & assist the trailer while performing portions of the test. Electric Brakes:If your trailer is equipped with electric brakes you will need a floor jack that enables you to jack up one wheel at a time. It is important to remember that the pins for the trailer plug will not …