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Harley Code B1405: What It Means and How to Fix It

by

Chase Manhattan

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Owner and Editor at The Wrench Network

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Hey y’all, it’s Chase Manhattan! I’m a life-long automotive and motorcycle enthusiast with a knack for diagnostics that I hope to share with you! Lately, I’ve been running my own motorcycle rental business, which you can read about here, and it has been a great experience that has allowed me to own numerous bikes that I probably couldn’t justify otherwise. Plus, it’s been a great way to experience new places while on vacation. If you haven’t heard of them before, I definitely recommend checking out the Riders-Share platform if you get the itch to ride while away from home, or if you want to explore a cheaper way to own and ride motorcycles!

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If you own a Harley-Davidson motorcycle, you may have encountered the B1405 diagnostic trouble code (DTC) at some point. This code indicates an EQ correlation error, which means that there is a problem with the audio system. The B1405 code can be triggered by a variety of issues, including an invalid or missing EQ, a speaker that is open or shorted, or a problem with the control module voltage reference output circuit.

When the B1405 code appears on your Harley-Davidson’s diagnostic display, you may notice some symptoms such as distorted or no sound from the speakers, or the radio not working at all. To diagnose and fix the issue, you may need to check the seat memory control module, the seat motor, or the amplifier. It’s also possible that the problem lies with the audio system wiring or connections.

If you’re not familiar with Harley-Davidson’s diagnostic process, it may be best to take your motorcycle to a qualified mechanic or dealership for repair. However, if you’re confident in your abilities, you can try to troubleshoot the issue yourself using the steps outlined in the search results. Keep in mind that diagnosing and fixing the B1405 code may require some technical knowledge and experience, so proceed with caution.

Understanding Diagnostic Trouble Codes

The Basics of DTC

If you own a Harley-Davidson motorcycle, it is essential to understand Diagnostic Trouble Codes (DTCs). These codes are generated by the Electronic Control Module (ECM) and indicate a problem with one or more of the bike’s systems.

DTCs are numerical codes that are displayed on the Harley-Davidson’s speedometer. These codes are used to diagnose problems with the bike’s engine, transmission, and other systems. By understanding these codes, you can quickly determine the source of the problem and take the necessary steps to fix it.

Harley-Specific Codes

Harley-Davidson uses a unique set of codes that are specific to their bikes. These codes are divided into categories known as “modules” in the onboard diagnostic system.

The categories include:

  • P Codes: ECM
  • C Codes: ABS
  • B Codes: Radio, Instruments, BCM
  • U Codes: Module communication

For example, the B1405 code is used for the Seat Memory Control Module. If this code is stored, you should check the Seat Motor and Seat Memory Control Module.

The Body Control Module (BCM) is responsible for controlling various electrical systems, such as the radio, speedometer, and lights. If you see a BCM code, it means that there is a problem with one of these systems.

In conclusion, understanding Diagnostic Trouble Codes is crucial for any Harley-Davidson owner. By knowing what these codes mean, you can quickly diagnose and fix any problems with your bike, ensuring that it runs smoothly and safely.

B1405 Code Explained

If you own a Harley-Davidson motorcycle and have encountered the B1405 trouble code, it can be a frustrating experience. However, understanding the symptoms and potential causes of this code can help you diagnose and fix the issue.

Symptoms of B1405

The B1405 trouble code is associated with the restraint control module (RCM) of your Harley-Davidson motorcycle. When this code appears, you may experience a number of symptoms, including:

  • The check engine light may illuminate on your dashboard
  • You may notice issues with your audio system, such as a lack of sound or poor sound quality
  • The seat memory control module may not function properly

Potential Causes

There are several potential causes of the B1405 trouble code. Some of the most common causes include:

  • A short circuit in the control module voltage reference output 2 circuit
  • Low voltage in the control module voltage reference output 2 circuit
  • High voltage in the control module voltage reference output 2 circuit
  • An EQ correlation error
  • An invalid or missing EQ

If you suspect that the B1405 trouble code is affecting your Harley-Davidson motorcycle, it is important to diagnose and fix the issue as soon as possible. This will help ensure that your motorcycle is functioning properly and that you can enjoy a safe and comfortable ride.

Diagnosis and Troubleshooting

If you’re experiencing issues with Harley code B1405, there are a few initial steps you can take to diagnose and troubleshoot the problem. Once you’ve taken these steps, you can move on to more advanced diagnostics if necessary.

Initial Steps

The first thing you should do when you encounter Harley code B1405 is to check the Diagnostic Trouble Codes (DTCs) using a scan tool. This will give you a better idea of what’s going on with your bike and help you determine the root cause of the problem.

Once you’ve checked the DTCs, you should also check the Controller Area Network (CAN) bus for any issues. The CAN bus is responsible for transmitting data between the various modules in your bike, so if there’s an issue with the bus, it can cause all sorts of problems.

Another thing to check is the Intake Air Temperature (IAT) sensor. If the IAT sensor is malfunctioning, it can cause the engine to run poorly and trigger Harley code B1405.

Advanced Diagnostics

If the initial steps don’t reveal the root cause of the problem, you may need to move on to more advanced diagnostics. This could involve using a multimeter to test various circuits and components on your bike.

One thing to keep in mind is that Harley code B1405 can be caused by a variety of issues, so it’s important to be thorough in your diagnostics. Some possible causes of Harley code B1405 include:

  • Control Module Voltage Reference Output 2 Circuit Short to Ground
  • Control Module Voltage Reference Output 2 Circuit Low Voltage
  • Control Module Voltage Reference Output 2 Circuit High Voltage
  • Deployment loop resistance out of range

By following these initial steps and performing advanced diagnostics as necessary, you should be able to diagnose and troubleshoot Harley code B1405 effectively. Remember to always refer to your bike’s service manual for specific instructions and procedures.

Electrical Components and Sensors

Battery and Charging System

The battery and charging system in your Harley-Davidson motorcycle are important electrical components that keep your motorcycle running smoothly. The battery provides power to start the engine and run the electrical system when the engine is not running. The charging system, on the other hand, keeps the battery charged and provides power to the electrical system when the engine is running.

If your battery is not charging properly, it could lead to a number of issues, including a dead battery, difficulty starting the engine, and electrical problems. Make sure to check your battery and charging system regularly to ensure they are working properly.

Sensor Operations

Harley-Davidson motorcycles are equipped with a variety of sensors that monitor various systems and components in your motorcycle. These sensors include the Vehicle Speed Sensor (VSS) and the Ignition Switch Sensor (ISS).

The VSS measures the speed of your motorcycle and sends that information to the Engine Control Unit (ECU). The ECU uses this information to adjust the fuel injection and ignition timing to optimize performance and fuel efficiency.

The ISS, on the other hand, monitors the position of the ignition switch and sends that information to the ECU. This allows the ECU to determine when the ignition is turned on and off and adjust the fuel injection and ignition timing accordingly.

If any of these sensors are not working properly, it could lead to issues with your motorcycle’s performance and fuel efficiency. Make sure to check your sensors regularly to ensure they are working properly.

Motorcycle Control Modules

Motorcycle control modules are essential components of the onboard diagnostic system. They are responsible for monitoring various systems and sensors on your motorcycle, detecting faults, and triggering fault codes when necessary. The two most important control modules on your Harley-Davidson motorcycle are the Engine Control Module (ECM) and the Body Control Module (BCM).

ECM and BCM Functions

The Engine Control Module (ECM) is responsible for monitoring and controlling the performance of the engine. It receives input from various sensors, including the throttle position sensor, oxygen sensor, and manifold absolute pressure sensor. Based on this input, it adjusts the fuel injection, ignition timing, and other engine parameters to optimize performance and reduce emissions.

The Body Control Module (BCM), on the other hand, is responsible for monitoring and controlling various systems outside of the engine. These include the lights, horn, turn signals, and security system. The BCM also communicates with other control modules on your motorcycle, such as the ABS module and the radio module.

Module Communication

The communication between control modules on your motorcycle is done through the Controller Area Network (CAN) bus. This is a network that connects all the control modules on your motorcycle and allows them to exchange information. When a fault is detected in one module, it can trigger a fault code in another module. For example, if the BCM detects a fault in the turn signal system, it can trigger a fault code in the ECM.

It’s important to note that the communication between control modules is bidirectional. This means that a fault in one module can also affect the performance of another module. For example, a fault in the ECM can affect the performance of the ABS module.

In conclusion, understanding the functions of the ECM and BCM and how they communicate with each other is essential to diagnosing and fixing faults on your Harley-Davidson motorcycle. By keeping your control modules in good working condition and monitoring fault codes, you can ensure that your motorcycle is running smoothly and safely.

Repair and Replacement Procedures

When to Replace Components

When you encounter the B1405 code in your Harley, it is important to determine whether a repair or replacement is necessary. In some cases, the issue may be resolved by simply resetting the code. However, if the code persists, it may be necessary to replace certain components.

One component that may need to be replaced is the battery. If the battery is not providing sufficient voltage, it may cause the B1405 code to appear. You can test the battery using a multimeter or take it to a professional for testing.

Another component that may need to be replaced is the ECM (Engine Control Module). If the ECM is not functioning properly, it may cause the B1405 code to appear. You can test the ECM using a diagnostic tool or take it to a professional for testing.

Step-by-Step Repair Guide

If you determine that a repair is necessary, follow these step-by-step instructions to resolve the B1405 code:

  1. Disconnect the battery to prevent any electrical shock or damage.
  2. Locate the Seat Memory Control Module and check the Seat Motor and Seat Memory Control Module for any issues.
  3. Check the Control Module Voltage Reference Output 2 Circuit for any shorts or low/high voltage issues.
  4. If you find any issues, repair or replace the affected component.
  5. Reconnect the battery and test the system to ensure the code has been resolved.

It is important to follow these steps carefully to avoid causing further damage to your Harley. If you are unsure about any of the steps, it is recommended that you seek the assistance of a professional mechanic.

Maintenance Tips to Avoid DTCs

If you want to avoid DTCs like the B1405 code on your Harley, regular maintenance is key. Here are some tips to help you keep your bike running smoothly and avoid trouble codes:

Regular Checks

Performing regular checks on your Harley can help you catch potential issues before they turn into bigger problems. Here are some things you should check on a regular basis:

  • Battery: Check the battery terminals for corrosion and make sure the battery is fully charged. A weak or dead battery can cause all sorts of problems, including DTCs.
  • Run/Stop Switch: Make sure the run/stop switch is in the correct position before starting your bike. If it’s in the wrong position, your bike may not start or may set off a DTC.
  • Security: Check that all bolts and screws are tight and secure. Loose parts can cause rattling and vibrations that can lead to DTCs.

Preventative Measures

In addition to regular checks, there are some preventative measures you can take to avoid DTCs:

  • Keep your bike clean: Dirt and debris can get into your bike’s sensors and cause problems. Regular cleaning can help prevent this.
  • Use the right fuel: Using the wrong type of fuel can cause your bike to run poorly and set off DTCs.
  • Ride your bike regularly: Letting your bike sit for long periods of time can cause the battery to drain and can lead to other issues. Regular use can help keep your bike in good condition.

By following these maintenance tips and performing regular checks, you can help prevent DTCs like the B1405 code on your Harley.

Common Harley-Davidson DTCs

If you own a Harley-Davidson, you may have encountered a Diagnostic Trouble Code (DTC) at some point. These codes are displayed on the odometer and indicate a problem with your motorcycle. In this section, we’ll go over some of the most frequent DTCs you may encounter and how to troubleshoot them.

List of Frequent Codes

Here are some of the most common DTCs that you may see on your Harley-Davidson:

  • B1103: LHCM internal error
  • B1153: Sidecar BAS short to ground
  • B1200: Fuel sender open/high
  • B1210: Fuel sender short/low
  • B1405: EQ correlation error

Troubleshooting Common Codes

If you see the B1103 DTC, it means there is an internal error in the Left Hand Control Module (LHCM). The LHCM controls the turn signals, horn, and high beam. To troubleshoot this issue, you can try switching the LHCM with the Right Hand Control Module (RHCM) to see if the problem persists. If it does, you may need to replace the LHCM.

The B1153 DTC indicates a short to ground in the Sidecar Bank Angle Sensor (BAS). This sensor detects if the sidecar is leaning too far and will shut off the engine if it does. To troubleshoot this issue, you can check the wiring and connections to the sensor. If they are fine, you may need to replace the sensor.

If you see the B1200 or B1210 DTC, it means there is an issue with the fuel sender. The fuel sender is responsible for measuring the amount of fuel in the tank and sending that information to the fuel gauge. To troubleshoot this issue, you can check the wiring and connections to the fuel sender. If they are fine, you may need to replace the fuel sender.

The B1405 DTC indicates an EQ correlation error. This error occurs when the audio system is not functioning properly. To troubleshoot this issue, you can try resetting the audio system by pressing and holding the odometer reset button. If that doesn’t work, you may need to take your motorcycle to a dealer for further diagnosis.

In conclusion, DTCs are a common occurrence in Harley-Davidson motorcycles. By understanding what these codes mean and how to troubleshoot them, you can save yourself time and money in the long run.

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