How To Turn On Bike Lights

Tips on Fixing Bike Lights That Won’t Work With Reasons Explained

One of its most-essential safety features, when you ride your bike, is its lights. If the light doesn’t work, it will fail to illuminate the roads at night. For an electric bike, it’s even more important as the battery will signal brakes to avoid collisions.

Thus, you can’t ride your e-bike when the light isn’t working. You would want to know how to turn on bike lights at that time. For this, you must know why the light isn’t working. Yes, you must know the reasons for a bike light not working. It helps you solve the problem faster and better.

Usually, a dead battery, loose connection, faulty switch, and fused bulbs are why the bike light is not working. It may happen due to a broken dynamo motor and a loose microcontroller. You need to diagnose the problem first. Then, you must solve the problem accordingly.

Why Is My Bike Light Not Working?


It can be worrisome when you start riding your bike and see the lights not working. Firstly, you will fail to warn others as you press the brakes. Secondly, you will become invisible at night and fail to see the roads. It happens because the failed light will not illuminate the roads.

Hence, it is important to investigate why a bike light is not working closely. The light failure may happen for the following reasons.

  • When the battery becomes dead, the light will stop working. The battery is responsible for providing the lights with the required energy. When the battery cells are dead, it fails to work. So, the lights can’t work anymore.
  • The battery connects with the lights with wiring. Sometimes, the wiring can be loose. It will, then, fail to transfer the energy from the battery to the lights. Naturally, the bike light won’t turn on when necessary.
  • Damaged wiring can also force the lights from functioning. When the wiring gets damaged, the circuit of the light fails to connect properly. It stops the lights from working.
  • In rare cases, a faulty switch can be the reason for non-functioning bike lights. There’s wiring and a circuit inside the on-off switch. The wiring can fail, and the switch can’t function consequently.
  • For electric bikes, there will be an electric microcontroller. It controls the lights of the e-bike. At times the microcontroller gets damaged or corrupted. It, too, stops the e-bike lights.
  • Finally, a damaged or broken dynamo motor is also responsible for the battery not working. It happens if your bike has dynamo-powered lights.

These are the 7 top and commonest reasons for bike battery not working. So, you need to check the lights’ connection, wiring, battery, and dynamo to fix the lights soon.

How to Turn On Bike Lights: Easy Steps To Follow

When you see the bike lights not turning on, you must fix them immediately. While you may wonder about fixing the bike lights, it is straightforward. You may easily follow our step-by-step guidelines to fix the bike lights soon.

Diagnose the problem thoroughly:

There can be single or multiple problems with bike batteries not working. So, you need to check the lights and their connections thoroughly. Remember that you should look at the lights closely. It helps you identify its reason for not turning on when needed easily.

You will need a multimeter to check the batteries and wiring. Firstly, set the multimeter in DC (Direct Current) mode. Then, attach the probes of it to the battery poles. Now, take a reading of the voltage multiple times.

If the battery voltage is at the required level, the problem can be loose wiring. So, check the wiring, switch, electric microcontroller, and dynamo motors. When you find the problem, you will have to start working to fix it.

Change the battery if it doesn’t work:

If the multimeter suggests that the battery isn’t working, you must replace it. For this, you need to disconnect the battery from its wiring. A flathead screwdriver and pliers set will be enough. Using the screwdriver, remove any screws from the battery. Similarly, disconnect the wiring with the pliers.

You may also look at the user manual of the e-bike for replacing the battery. At times, you might need to recharge the battery for reusing it. It will be a good solution if your bike has a conventional lead-acid battery.

Lead-acid batteries often become dead when the cells lose their power. You can reuse it by reaching the cells from a nearby battery shop.

Cleaning the battery and switch:

The battery and switch have metal parts inside them. Sometimes, they can catch rust and start corroding. Also, residues and dust can develop on the metal parts. When it happens, the battery and switch will malfunction.

As a result, the lights won’t turn on when you press the switch. The easiest solution is to remove the rust and corrosion. Apply a few drops of contact cleaner to remove the residues. You can choose WD 40 Specialist Contact Cleaner. It is excellent at removing dust, oil build-ups, dirt, etc. Also, it is made for electrical equipment too. 

After applying the contact cleaner, wait for a few minutes. Then, wipe it off using cotton. You may have to repeat the process multiple times. A few people may suggest you use a file to remove the residues from the top layer of the battery. We strongly discourage you from using the file.

Fixing the wiring of the lights:

If replacing, recharging, or cleaning the battery and switch don’t work, you must check the wiring. If you find loose or faulty wiring, disconnect it from the lights. The pliers set will work fine for disconnecting the wirings.

You may also follow the user manual to replace the wiring of the lights. To fix it, follow the steps:

  • Cut and open up the wiring
  • Find the insulation of the wires and strip it off accurately
  • Add the latest heat-sink tubes around it
  • Finally, solder the wiring with a heat gun and soldering elements
  • Alternatively, you may use a heat gun to apply the heat-sink tubed and soldering

You must avoid soldering the flexible or bending parts of the wiring. It will fix the loose connection issue of bike lights.

Replacing broken or old bulbs:

If your bike has the traditional incandescent or halogen bulbs, they can stop working after a certain period. These lights will burn over after a few thousand hours of illumination. All you need is to replace the old bulbs.

Furthermore, the LED bulbs may also get broken due to collisions. You will need to replace it too when the LED lights get broken. The cost will be around $5, so it is affordable.

Fixing the dynamo:

If everything fails to turn on the lights, the problem may be with the dynamo of your bike. A dynamo consists of two output electrodes and a rotating part. These electrodes and rotatory systems are made of metals. Over the years, these metal parts can erode and get damaged severely.

When the dynamo gets damaged, remove it entirely from your bike. Then install direct battery-powered lights instead of the dynamos. These lights are affordable and long-lasting.

Frequently Asked Questions

Why is my bike light not working?

In most cases, drained batteries or loose wiring will be responsible for the lights not working in bikes. If you are unlucky, it could be due to a malfunctioning switch or microcontroller.

Why is my bike headlight always on?

Many American states have forced e-bikes to use the AHO system. It keeps the headlight on all day. You must check the AHO system thoroughly if your headlight is always turned on.

How to turn on bike lights?

After powering up the bike, press the switch for 3 seconds. It will be enough to turn on the lights on your bike.


Turning on bike lights that have stopped working requires you a bit of labor and time. You must start by checking and identifying the problem. Then, you may find the reasons for bike lights not working. It includes a failed battery, loose or damaged wiring, dynamo, and broken bulbs. Depending on the cause of the bike lights stopping working, you may follow our suggestions to fix it.

Recent Posts