cartoon man tangled up in Tru-Tone Christmas lights


If you've run into trouble with your new lights, don't fret, we're here to help!


If your entire Tru-Tone light string isn’t lighting up, jump ahead.

If a single bulb isn’t lighting up, try the following:

1: Try the bulb in a different socket which you know is working – If the bulb still doesn’t light, you may have a damaged or faulty bulb and should contact us for a quick replacement.

2: The bulb may not be fully threaded into the socket. -It may also be that you have cross-threaded a bulb, where it may meet resistance before being fully threaded into the socket. This can happen to the best of us and with any threaded bulbs or light strings. You can usually recognize this as the bulb will visually not be threaded into the socket as far or may be positioned on an angle to the socket. 


Unscrew the bulb and attempt to re-thread, varying the starting position of your rotation into the socket while maintaining light pressure. If you experience the bulb wanting to torque on an angle into the socket, reverse your threading until the bulb settles straightly into the socket before turning clockwise into the socket again. This may take a few tries but almost always resolves this problem. 

You may also experience slightly more tension when threading a bulb correctly into the socket. If it is not crooked, you should be able to push past this tension to fully thread the bulb. 

3: Try a different bulb in the same socket. – If no bulbs will light in the same socket, unplug the string, remove the bulb, and check the contacts on the bottom and side of the socket. On rare occasion, these get bent out of alignment or pushed too deep to make contact. ALWAYS UNPLUG THE STRING OR DEVICE THAT CONTAINS THE SOCKET BEFORE ATTEMPTING ANY ADJUSTMENTS TO THE CONTACTS. Once the device is unplugged you can use a small screwdriver or tweezers to attempt to bend the contact back into place.

View inside of a Christmas light string socket

4: If some bulbs light, but many do not, this may be a very rare incompatibility with the light string you are using. Some light strings from big box retailers were sold in a set with matched bulbs. The sockets are notably taller and without a flared opening which can prevent other bulbs from fully threading and making contact. Glass bulbs have some variation in their size and shape, which is why some may successful make contact. Standard sockets found on the vast majority of light strings are shorter with a flared opening. While you could attempt to shorten the sockets, it’s probably best to obtain standard light strings found many places online or locally. If you are buying light strings that come with bulbs, pay attention to the style of socket.  

Christmas light string sockets

If your entire Tru-Tone light string isn’t lighting up, the most likely cause is a blown fuse. These can be replaced and are located in the plug of the light string.


Always unplug your light string before replacing fuses. (note: our Deluxe fabric-covered light strings do not have fuses)

Each light string has two 3.6 x 10 mm quick-acting 3A Fuses, and comes with a small paper packet of replacements attached near the plug. They are also the same fuses that work with common mini-light strings and are often available from the Christmas light section at your local stores, or you can reach out to us for an additional set. 

illustration of Christmas light fuses
Christmas light fuses

If the light string goes out again immediately after replacing the fuses, this is likely caused by a short. You may be able to locate the bulb or socket that are causing the short, indicated by a flash or spark when the string goes out, or by dark burn marks around the bulb and socket.


The fastest process to determine the cause of an electrical short is to start with an empty light string (with un-blown fuses), plugged into an outlet, ideally one with an integrated circuit breaker for convenience if you have one. Begin screwing in one bulb at a time,  until the issue/short is discovered. Unplug the string or device and remove the bulb from the socket to inspect both the bulb and socket.  If the EMPTY light string trips the fuses, there's likely a defect inside the plug and will need to be replaced by us.

While uncommon,  causes of a short in a light string can be an improperly threaded bulb (inserted on an angle or cross-threaded), a faulty bulb (sometimes with a small strand of wire connecting the side and bottom of the base) or a misaligned contact inside the socket (See Step 3 above). If the socket contacts appear to be misaligned, follow the directions in Step 3 above to repair it. If the bulb or light string appears to be the problem contact Tru-Tone for a speedy replacement. 

Christmas light bulb with stray solder wire