Roof Marker Lights Not Working: Troubleshooting Guide

You’re on the road, and the sun is starting to set. You turned on the rood marker lights but noticed it was not working. But, it’s the law by the state that you must turn on the lights, not just for other drivers, but also for yours.

But the last night, it was working fine. What happened? Why are the roof marker lights not working?

The reason might be as simple as a blown bulb or light, or maybe a fuse got blown. Besides that, there could be a switch issue, or perhaps the connector got loose. Sometimes dirt buildup in the wire or connector connections might cause this issue.

Don’t worry! Whatever the reason, we’ll go to the bottom of this and start fixing it! Let’s get to check the problem.

How Do You Check Marker Lights On A Trailer?

How Do You Check Marker Lights On A Trailer
Source: rvrepairclub

The marker lights are essential when you’re on the road, not just for other drivers but also for you. It is crucial to ensure the roof marker lights are in good condition and ready to go.

Now, there are several ways to check whether the marker lights are ok or not. We’re going through the steps briefly so you have a decent idea.

Way #1: Check The Marker Lights With A Multimeter

The first easy method we are going to use is a multimeter. You will find a green contact in the trailer rod. You must connect the multimeter to that rod.

Then, You should set the mode for the multimeter to continuity. There is a red wire in the multimeter, right? Now, that that, and connect it to the joint where the green wire connected.

Now, you need a screwdriver to disconnect the screws of the board of that light, which isn’t working. In this part, touch that green contact joint part. The reading in the multimeter should be between .6 to .7 ohms.

If there’s no reading on that wire, there is something wrong with this wire. Rerun the process with another wire connected to the marker light board. You will find if there is anything wrong with the marker lights wire.

Way #2: Manually Checking The Components

Before starting and checking the process, you must ensure that the connector is tight between the car and the wires.

Go through the components connected with the roof marker lights, such as brakes, hazard lights, and blinker lights. Double-check which lights are working and which aren’t.

Sometimes the case might be the lights are blown, and you just need to unscrew the parts with a screwdriver and replace that bulb. But sometimes, that’s not the case!

To ensure this, you need to unplug the black trailer cord. Now, you can test and confirm if all the connections are working. You can quickly pinpoint the faulty cable or wire causing this problem.

But there is another way to find the problem. You can check the roof marker lights by connecting the tester with the car’s connector. There are many options you will find in the market for connectors. 

If the lights are turned not green, then there is a problem with that particular light or in the connection. But always ensure that the fuse in the circuit box is fully operating.

Way #3: Find If There Is Any Corrosion In The Connections

Sometimes, there might be dirt or anything that might be causing the problem. Now, in those cases, you need to manually check the connections among all the connected components with the lights.

There is grit sandpaper you might use. In the process, you might find if there is any dirt corroded in any connection or not. That way, it might lead you to the problem.

As we discussed all the ways we can check the car parts, some things might be causing the problem. But, before that, we need some tools to fix the problem.

Required Tools to Fix the Roof Marker Lights Problem

Why is my Roof Marker Lights Not Working

Whatever the problem, we need a few tools to start and fix the problem. We made the process easy by listing down a list of the tools. Here’s what you need.

A screwdriver: Whatever the problem, a screwdriver always comes in handy, from disconnecting screws to many other things.

A multimeter: We need a multimeter to check whether there is a problem with any wire or connection.

A light tester: As the issue is directly related to the lights, the light tester will make the process easier, and the work will be efficient.

A circuit breaker tester: To check whether there is any problem with the circuit breaker, we need a tester. 

Grit sandpaper: The grit sandpaper will be necessary when dealing with any dirt or connection corrosion in any connection.

A new fuse: If you find any blown fuse in your circuit box (Just in case).

Grease: To maintain and ensure the wire connection is up and working correctly.

More or less, these are the items we need to fix the problem. Now, let’s get into solving the issue.

Roof Marker Lights Not Working [Reasons & Fixes]

Roof Marker Lights Not Working Troubleshooting Guide

There could be a simple reason behind this problem or could be multiple. As we already showed you what to check and how to check the components to ensure where the problem lies, you will be able to start fixing the problem one by one yourself.

Let’s start with the apparent reason!

The Bulb Got Blown, Or Brunt

Sometimes, the apparent reason is the bulb itself. As we already showed how to check the bulbs or lights with a light tester, this part should be easy.

Most of the time bulb needs to be replaced with a new one. Here’s how you’re going to do it.

  • First, you must turn off all the switches connected to the roof marker lights, such as the light switch and main electric switch at the circuit board.
  • Get a screwdriver and unscrew all the nuts of the faceplate of the light.
  • Then, unscrew the brunt or blown bulb.
  • Get a new bulb with the same voltage as the previous one, and screw that in the faceplate.
  • Turn on the power to check whether the bulb is working or not.

That should solve the problem. If that doesn’t work either, the problem lies somewhere else. We’ll start with the fuse and switch.

Fuse Got Blown

The problem could be as simple as a blown fuse. Sometimes if a power surge or something else like that might cause the fuse to be blown, you should check that too.

Go to the circuit or engine board and check whether that’s the case. You just need to get a new one and replace that with the blown one.

  • Take off the lid of the fuse or fuse box.
  • Then, disconnect or take off the blown fuse.
  • You will find a plug socket. From there, take off the DRL fuse.
  • And replace the fuse with a new one with the exact model.

That might do the job!

Switch Issue

Sometimes, the power switch that provides the power might be the problem. Or sometimes the dash switch could be the problem too.

Now, how to fix this?

  • Disassemble the switch part.
  • Then, swap or replace with a similar relay.
  • Screw the board properly.
  • Check whether the switches are working.

And that’s it! Easy, right?

Connection Got Loose

There could be one or multiple issues with the connection that might cause the problem. The first one we’ll discuss is the connector.

To check and fix the problem, here is what you should do;

  • The first step is to turn off the engine.
  • Then, inspect the light assembly.
  • It would help if you had a screwdriver to unscrew the nuts from the assembly.
  • You will find the connector there. Pull that and take it back to the engine apartment.
  • If you find the connector loose, you need to reconnect or tighten it.
  • If the connector is broken, you need to get a new one and replace it.
  • Screw back everything and turn on the engine. 

Check if the solution worked, and you’re good to go! But, sometimes, a problem might arise in the circuit box issue and a loose connection.

Check if that’s the case and tighten any connection if anything loosens. If that doesn’t solve the problem, there is only one issue left to mention: the wire problem.

Wire Issue

The wiring can cause many problems, including roof marker lights not working. Some wires operate into the frame of the RV or camper or the vehicle you’re running.

If you find any broken part, the wire in there could be the reason. But, if that’s not the case, the wires on the inside could be the cause.

As we know, different types of wires are connected with the other pins. We already discussed a 7-pin trailer running light not working issue. The problem could be lying there.

Or the ground wire could be a problem too. Now, whatever and wherever the problem might be, we need to inspect and fix the problem one by one.

First, there could be corrosion on the wire connections too. So, we need to clean that. The grit sandpaper and grease comes in handy in these situations.

  • Carefully inspect the connection of the wires and see if there’s any buildup of dirt or something.
  • You need around 130 grit sandpaper. And use the sandpapers to remove any buildup on those connections.
  • Place them for not more than twenty-five seconds.
  • Remember not to push or scrape the papers too hard.
  • That might remove any buildup on those connections.
  • After that, spray the connection cleaner.
  • Put some grease to make the connections as new again. But don’t spray too much.
  • You can also use electrical tape on the wires to connect them.
  • Reconnect the wire with the connector.

If you find any broken or damaged wire, you need to replace those broken parts. And you’re good to go!

Last Words

That was all from us regarding the roof marker lights not working. We hope you found your exact problem and can solve that problem.

You can solve most problems yourself, regardless of the situation’s complexity. Let us know if there’s anything we can do.

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