One of the facts of life when you own a recreational vehicle is the problem of intermittent running lights. Fortunately, there are only two predominant causes for this problem: road vibrations and corrosion. This fact narrows down the troubleshooting process.
Corrosion erodes the electrical contacts on the running lights, causing the lighting malfunction. Road vibrations loosen connections, thereby disrupting the flow of current. In fact, the majority of problems with exterior lighting can easily be solved with a few spare bulbs and fuses that are stored in a handy and accessible spot.
If the running lights are not working, one of the first things to check is the presence of a blown fuse. If all of the lights are connected on the same circuit and one of the fuses is blown, then the lights will not work.
If the turn signals are not working, locate the fuse block that contains the circuit for them. Take out the fuse and inspect it visually. Look to see if the filament inside the fuse is broken. If the filament is broken, then you know you have found the problem.
Sometimes, however, the fuse may appear to be in good condition, but it really is dysfunctional. To rule that instance out, take a new fuse that has the same rating and insert it into the proper location. If you don’t have any spare fuses available, use the VOM on your Ohm scale to check for continuity through the fuse. If the problem is a short, and the next fuse that you insert shorts out as well, then you will need to use the circuit breaker test leads from your tool kit. While substituting the test leads for the fuse, search for the short.
Poor electrical contact in the wiring connector between the trailer and the tow vehicle can cause an entire circuit to fail. To prevent this from happening in the first place, simply keep both the plug and the socket covered in sturdy plastic whenever they are disconnected.
Poor electrical contact is typically caused by corrosion. Corrosion occurs after water has gotten into either the trailer plug or the tow vehicle socket. This can be remedied with a good treatment from a spray can of electrical contact cleaner. This can typically be purchased at any hardware, electronics, or recreational vehicle location.
Quite possibly the easiest solution to the problem of nonworking lights is the discovery of a single burned out bulb. Simply remove the lens cover for the bulb and look to see if the filament is broken. If it is broken, replace the bulb.
However, if the filament looks good, then the lamp may have corrosion on the inside of the fixture. Take a look at the connections to see if they are firmly attached and clean. If corrosion exists or if the connections are dirty, clean it up. Take the bulb and give it a once over with fine sandpaper on its base. If you do not have find sandpaper, do not use coarse. Instead, get some emery cloth to use.
Check also to see if the contact strip and its clip are clean and free of corrosion. If not, clean them and then use fine sandpaper to burnish them. Finally, investigate to see if the contact strip actually touches the tip of the bulb, as it should. If it doesn’t, then try bending it gently until it does. If the fixture has a great deal of corrosion, ignore all these steps and simply replace the entire unit.
If you are dealing with corrosion, you will need to take a few precautionary steps to prevent the problem from continuing in the future. Corrosion is typically caused by water seepage, in this case, from the lens. Use a bit of silicone sealant on the edges of the lens to prevent any future corrosion. It is best to do this prior to placing the lens in the fixture.
If the light flickers, especially when you tap it, then a bad ground is probably at the root of the problem. In order to check for a bad ground, you'll need to take the lens off. Take an alligator lead, or a piece of wire if you don't have an alligator lead. Attach one end of the lead to one side of the bulb's base. Pick up the other end of the lead or wire and touch something that is bare metal, such as the lamp's mounting screws or an aluminum windowsill on the trailer. If the result is a lit bulb, then a bad ground is indeed the problem.
Most trailer lamps are grounded by either a double wire set up or a single wire set up. Trailers with a nonmetallic mounting surface are required to have the two-wire set up. To check to see which is the case with your trailer, remove the cover of the lens. If you see only a single wire, then the ground path is through one of the mounting screws and into the aluminum skin on the trailer. Tightening the screw usually solves this problem. If this does not solve the grounding problem, replace the screw with one that is slightly larger, typically the next size.
If you see two separate wires when you remove the lens cover, trace the ground wire. The ground wire usually is attached to any point on the chassis of the trailer. Check to make sure that this wire is not broken and that it is securely attached, and fix it if need be.
Dim lights are indicative of the hot lead that goes to the lights shorting current into the chassis. Check this wire out. If you discover worn insulation, use electrical tape to repair it. If the wiring has been spliced together, then you will also need to check out the connectors on them to look for possible water damage and corrosion.
In some cases, the trailer may have a harness that runs along the frame rails. In-line fuses may be located within the harness. You will need to check for the fuses. One of the easiest ways to do this is to use a 12-volt test light. Once you have located the fuses, you can begin the trial and error process to check for a malfunctioning fuse.
Additionally, road vibrations can cause the wire nuts to loosen in the rear lamp assemblies. Check the wires and the nuts to make sure that they are connected and tight. Use electrical tape to wrap the nuts in the first place to prevent this from happening.
Always remember to check your lights to see that they are in good working order prior to any trip. Complete the necessary repairs in a timely fashion. Purchase spare parts and keep them in a handy and secure location. If you take care of your trailer, then it will take care of you.