Harley Davidson LED Turn Signal Problems & Solutions: Harley Turn Signal Module Replacement

This article discusses Harley Davidson LED turn signal problems- Harley turn signal module replacement and troubleshooting technique that every Harley owner must get familiar with.

Turn signal problems can be a big deal, especially if you do not have technical experience.

Even with technical experience, troubleshooting this issue can be confusing, considering how congested and interwoven the connections and wirings are.

Using the owner’s manual, you can easily identify the wires and various components that make up the lighting unit.

This allows you to know the various connections and how to access, diagnose, and perform the necessary replacement on faulty components when necessary.

We will discuss the most occurring or common turn signal problems, the steps you need to take to diagnose each problem, and how you can fix these problems as soon as possible. 

In the end, you will know how to correct the Harley Davidson LED turn signal problems without having to panic whenever they occur.

How to Diagnose Harley Led Turn Signal is Bad?

Before the turn signal goes bad completely, the first sign you will notice is that it may blink for a moment then stop after you turn it on. Eventually, it won’t light up on the indicator panel anymore.

Common Harley Davidson LED Turn Signal Problems

This section discusses the common LED turn signal problems and how to troubleshoot/ diagnose these issues and solve them.

01. Change in flashing rate- when the turn signal lights flash or blink too fast or too slow

Harley owners may experience this issue once in a while. This issue can occur based on several factors. The following are steps to take to find out the possible issues and correct them.

  • You may experience this problem after flasher or bulb replacement. If that is the case, it could be that the bulb replacement wasn’t done correctly.
  • The turn lights may flash faster or slower than usual when the bulbs are burned out. So, check the bulbs accordingly to confirm if they are in a good state.
  • Check the power connections to confirm if they are still in good condition.  A bad power connection can affect the flashing rate.
  • The turn signal lights may flash at irregular rates if the turn switch connection is not as firm as it should be. Check for loose connection.
  • Check if the battery is not excessively charged. An overcharged battery may cause a change in flashing rate.
  • Check if the battery is not undercharged. A battery that is not adequately charged may cause the signal lights to flash at a very slow rate.


  • Ensure the new bulbs or replaced bulbs are the ideal/perfect fit for your motorcycle. Ensure you check and confirm compatibility before the installation.
  • Make sure the battery is charged normally, and monitor the flashing rate as frequently as you can.
  • Ensure the alternator is in good condition from time to time. When the alternator is bad or faulty, it may be responsible for undercharging the battery.

02. Turn signal lights response failure: This is when all the turn signal lights fail to come on

This is another issue many Harley owners face. Sometimes, all the turn signal lights will become unresponsive.

Below are the steps you need to take to find out the factors that may be responsible for this issue:

  • Check out the signal lights component. A response failure may occur when the flasher unit is bad due to a blown-fuse or faulty switch.
  • Check if the bulbs are in good condition. A faulty bulb may be a culprit.
  • Confirm if the ground connection is working optimally. A faulty ground connection may be responsible for response failure.


  • Ensure you check the bulb socket, housing, and connector to confirm if they are in good condition. Look out for any indication of corrosion, overheating, and damage.
  • In case any of the electrical connection is broken, try to replace or fix them.

Before you perform this routine check, ensure the connector has been unplugged.

03. Turn signal lights fail to flash: This is when the turn signal lights come on but fail to flash

This issue is very easy to notice. This is when the turn signal lights come on but won’t flash or blink. The following are major factors that may be responsible for this problem:

  • Check for a burned-out or a bad bulb. This is one of the common reasons for this problem.
  • In case the bulb is working fine, you may want to check if the flasher unit and the signal switch are working fine. If the flasher unit is lousy or when the signal switch is bad, the signal lights may fail to flicker.
  • You can also check if the circuit fuse is in perfect condition. A blown-fuse is another thing that may cause this problem.


  • Replace burned-out fuse. Also, a bad bulb, flasher unit, and signal switch must be replaced accordingly.
  • Make sure the circuit connections are in perfect condition. They should be properly plugged, free from rust and corrosion, and fastened rightly.
  • Ensure the connection between the circuits, flasher, and the turn signal switch is adequate.
  • Ensure the connection between the ignition switch and the flasher is in the right condition.
  • Make sure you correct or fix any inappropriate contact between the power side connection and the signal switch.

04. Turn indicators fail to work, but the turn signals are active

This is when the signal lights work perfectly from the outside, but the indicator lights do not come on.

Follow the steps below to find out the possible causes:

  • Check if the indicator bulbs are in good condition. When the indicator bulbs are bad or blown-out, there is no way they would illuminate.
  • Find out if the bulb sockets are in perfect condition. Corroded bulb sockets may prevent the indicator lights from coming on.
  • Check for bad ground connection.
  • Check for any issue or problem with the flasher unit.


  • Go through the owner’s manual and check through the manufacturer’s recommendation for bulb replacement and panel configuration.
  • Check for faults or issues in the flasher unit and indicator light and get them fixed.
  • If you are replacing the bulbs, ensure the installation is done properly.

05. Turn signal lights fail to turn off

This problem occurs when there is a mechanical fault with the signal switch. In most cases, the problem has no connection with the electrical system.

The most popular scenario is when you put on the signal light while trying to turn left or right, and it still keeps flashing after turning it off.

Below are possible causes of this issue and what you should look out for when troubleshooting the cause of the problem.

  • Check if the cancelling finger is damaged or faulty. This component can be found inside the switch.
  • Check if the cancelling cam or clock spring is in good condition. If any of these components is faulty, the signal light may fail to turn off.


  • For a damaged cancelling finger, make sure you get the signal switch replaced to fix the problem.
  • For faulty cancelling cam, get this component reassembled or replaced to correct the issue.

Overall, the provided solutions may vary from one model of the Harley Davidson to another.

Although you do not need an expert to resolve these problems, you will need to go through the owner’s manual and understand how each component works, the processes involved, and the tools you need if necessary.

In case you are confused and do not know what you need to do specifically, ensure you reach out to a professional that understands all the necessary details.

Trying to fix any of these problems without a proper understanding of how they should be approached may lead to other problems.

06. The turn signal lights work well, but the hazard lights won’t come on

In some cases, the emergency lights, which are also called the hazard lights, and the signal lights make use of the same circuit.

If your signal lights turn on, but the emergency lights fail to illuminate, follow the steps below to diagnose the possible issues.

  • Check the emergency flasher unit to ensure it is in a perfect state.
  • In case there is nothing wrong with the flasher unit, check the fuse.
  • If the fuse and the flasher units happen to be in good working condition, you can check the turn signal switch for a faulty connection. Check the specific part of the circuit that links the emergency light flasher to the turn signal switch.
  • Check the electrical open in the wiring that links directly to the external lights.

Solutions: Once you have identified the possible cause of the problem, consult your owner’s manual to find out how the affected component, part, or unit can be correctly replaced.

Harley’s Turn Signal Module Replacement DIY

The removal or replacement of a faulty turn signal module is what most Harley owners can do.

This section discusses the steps you need to follow to replace your turn signal successfully.

Front Turn Signal Replacement

  1. Disable your bike’s electrical system by removing the Maxi-fuse
  2. Remove your bike’s seat to allow easy removal of the gas tank
  3. Keep the gas tank away from the bike
  4. Disconnect the turn signal connector module or unit from the frame
  5. Disconnect the left front turn signal by unplugging the black and violet wire connectors, or the right front turn signal by unplugging the black and brown wire connectors
  6. Remove the turn signal wiring out of your bike to allow easy removal of the faulty turn signal.
  7. Insert the new turn signal ball post under the handlebar switch pod, position the turn signal, facing the front of the motorcycle
  8. Tighten the Allen head bolt back to its position
  9. Connect the turn signal wiring and plug it into the right terminals
  10. Mount the gas tank back onto the bike, and connect the fuel and vacuum hoses accordingly
  11. Reconnect the Maxi-fuse

Rear Turn Signal Replacement

  1. Follow the first 3 steps as indicated in the front turn signal replacement procedure
  2. Disconnect the taillight lens
  3. Disconnect the left rear turn signal by unplugging the black and violet wire connectors, or the right rear turn signal by unplugging the black and brown wire connectors
  4. Go to the rear fender’s inner wall and loosen the rear turn signal nut
  5. Remove the turn signal from the strut cover. The wiring inclusive
  6. Reinstall the strut cover and the new turn signal by connecting them to the rear fender strut
  7. Route the wire correctly- from the rear fender to the taillight base
  8. Plug the connectors into the right terminals
  9. Reinstall the taillight lens
  10. Reconnect the Maxi-fuse


  • Screwdriver
  • 1/2-inch socket
  • 1/4-inch Allen wrench
  • Torque wrench
  • 5/8-inch socket


On average, it takes about 2 hours to complete the installation process.

FAQ’s Harley Davidson Turn Signal Module

Why do my turn signal lights fail to come on?

The likely reason your signal lights may not come on is due to a faulty flasher signal. Whenever you experience this, check the flasher signal thoroughly, or seek the help of an expert.

Why do my signal lights come up when I press the emergency switch?

If your signal lights also come on when you press the emergency switch, the switch may be multi-functional. 

You can seek a temporary solution. This involves pressing the hazard switch gently so that it won’t trigger the turn signal lights also.

The permanent fix is to replace the switch as soon as possible to allow each unit to work independently.

While looking for the replacement switch to buy, make sure you are careful with your design choice. If possible, check for compatibility before you finally pay for it.

How do I know my signal switch is faulty or going bad?

The easiest way to detect or find out if your turn signal switch has started failing or going bad is when the switch can’t adequately turn on/off the signal.

Whenever I try to switch on the left signal lights, it also turns on the right, front, and back lights. What should I do?

If you experience this problem at any point in time, the first thing you should do is to check for loose wires.

To find out the exact source of the problem, use a test light and wiring diagram. The wiring diagram and test light can be found in the owner’s manual that comes with your motorcycle.

Why are my signal lights not working, but my flashers are working perfectly?

This issue can be a result of a faulty/damaged turn-signal switch. 

Go through your owner’s manual to see how you can use the test light to conduct a quick check on the part of the circuit that may be responsible for the problem.

What could be the issue? My signal lights flash correctly when my motorcycle is parked, but not when I drive.

This possible problem could be due to a faulty circuit relay. Check the circuit relay to see if it is a perfect condition. In case the relay is not the issue, the circuit itself could be a possible culprit.


This article has explained Harley Davidson LED turn signal problems- Harley turn signal module replacement by providing relevant information.

Our aim is to help you identify the problems and fix them faster so that you can drive safely on the road always.

Now that you understand the many reasons why the turn signal may fail, you must check all the lights from time to time, pick out the one that is not performing optimally and replace it accordingly.

When you understand what to look out for in the turn signal lights, it becomes easier and faster to fix these issues.