Why does only one light work on my trailer?
If the lights on one side still aren’t working, you may have a break in the wire. To test for a broken wire, check the color of the wire going to the socket and then find that wire on the connector in front. Probe inside the socket with the tester (you’ll see the color of the wire that connects to the socket inside).
Why are the lights on my tow truck not working?
Trailer light problems can be traced to any point in either the tow vehicle’s electrical system or trailer wiring, so visual inspection and testing are the first things to do. 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.
What should I do if my trailer lights are not working?
Usually the best way to troubleshoot your wiring issue is to disconnect the trailer from the truck’s 4-pole and test each one individually. However, based on your description of the problem – all trailer lights working until you turn on the vehicle headlights – there is one most-likely cause that should be easy to correct.
How to tell if a tow light is on or off?
On the 4-pole pin for the yellow wire you should detect a steady signal when the brake is pressed and an on-and-off signal when the left turn signal is on. On the pin for the green wire you should detect a steady signal when the brake is pressed and an on-and-off signal when the right turn signal is on.
Why are the tail lights on my car not working?
If the wiring is all correct then you will need to check the trailer connector on the vehicle and trailer for a ground connection issue, or a short on the tail light circuit on the trailer. Open them up and make sure there is no white or green corrosion causing an issue inside the connectors.
Trailer light problems can be traced to any point in either the tow vehicle’s electrical system or trailer wiring, so visual inspection and testing are the first things to do. 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.
What to do if your trailer light does not work?
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.
If the wiring is all correct then you will need to check the trailer connector on the vehicle and trailer for a ground connection issue, or a short on the tail light circuit on the trailer. Open them up and make sure there is no white or green corrosion causing an issue inside the connectors.
When to troubleshoot a tow vehicle wiring problem?
A lighting problem can originate at any point along the wiring on either the tow vehicle or the trailer, so it is important to determine not only what is causing the problem, but where it is located. The question the troubleshooter will find themselves asking is “There are so many things to check. Where do I start?”
