What does a generator control module do?


Generator sets use programmable microprocessor-based controller modules. These controllers can monitor any adjustments or parameters to the generator set's electrical or mechanical components.

A generator control module is a type of electronic control unit that you use to regulate the operation of a generator. It monitors and controls the generator's engine speed, output voltage, and frequency. The module also protects against generator overloading and engine overheating.

Additionally, they offer the generator set with all required mechanical and electrical safeguards. The user can start or stop the generating set using the control module. They also monitor and manage the generating set's measuring and protection circuits. The controller unit's ability to be programmed adds to its versatility under various circumstances.


If you want to ensure that the generator set starts and supplies power when the mains power goes out, you use automatic control panels in applications where the generator set is a secondary or backup power source for the mains electricity.

In applications where the generator set is the primary or significant power source, you use manual control panels. They start and supply electricity as needed and when you need to start the generator.

The microprocessor-based controller manages everything that you need to do in both scenarios and panels, including monitoring the mains power, starting or stopping the generator set depending on the state of the mains power, protecting the engine/alternator or any other equipment on the generator set system, and transferring load between the mains and the generator set.

By pressing the corresponding button on the front panel, you can switch between the different operation modes. If you do this while a generator set is running, the behavior of the generator set will change according to the operation mode you choose. For instance, if the "MANUAL/RUN" mode is selected, the controller enters manual mode. Any activity requiring manual interference, such as starting or stopping the generator set, requires manual intervention.


You halted or kept stopped the generating set at rest using this mode. When you choose this mode on the controller, the generator set either does not operate or, if it is, ceases. If you want to transfer the load to the mains and supply the load from the mains, you open the generator set contactor, and the mains contactor is closed.

A single click of the STOP button causes the controller to initiate the standard "stopping sequence" and causes the engine to shut off after an "engine cooldown." It will help if you hit the STOP button twice to stop the generator set promptly. Read here; How to safely turn off the generator when the power comes back.


In this mode, you automatically turn on the generator and the load alternates between the mains and the generator set.

If at least one of the phase voltages at the side of the main exceeds predefined limits, the engine cranks for pre-determined periods and with pre-set intervals when you select this mode on the controller. The controller stops spinning as soon as the diesel engine kicks on.

The generator set contactor closes the generator phase voltages once the "engine heats up" and "contactor" timers have finished running. After that, you change the load's source from the mains to the generator set.

The controller starts counting down a "mains waiting timer" to ensure that the mains voltages are back and proper until all phase voltages on the main's side have returned to the pre-configured tolerance limits. You start to supply around the load from the mains once more after the generator set contactor is opened and the mains contactor is closed.

The controller shuts the engine off following a successful load transfer back to the mains after a "cooldown timer." The generator set returns to its "standby" rest position to wait for the subsequent major failure once you shut off the engine finally.

The AUTO led will flash, and the generator set will operate as though it is in STOP mode if a weekly schedule prevents the running of the generator set.


While the 'mains' is still on, this mode tests the generator with or without a load. When you choose this mode on the controller, the generator operates much like in AUTO mode, except if the mains are on, the mains contactor won't open. In addition, the main contactor opens, and the generator set contactor closes if the mains are unavailable.

You transfer the load back to the mains when turned on, but the engine continues to run unless you choose another mode. In this situation, the controller should be set to another way of operation (such as AUTO or STOP) to stop the engine.


When the mains are still on, or there are no mains, this mode runs the generator with or without a load. The engine will start once you choose this option on the controller. It would help if you used the contactor buttons on the front panel for manual operation to switch the load between the generator set and the mains in this mode.

How to troubleshoot a diesel engine generator's control module

Troubleshooting a diesel engine generator's control module can be a complex process, and it is often best to consult the manufacturer's instructions or a qualified repair technician for specific guidance. However, here are some general steps that may be helpful:

  1. Check the generator's manual and make sure you understand how the control module works and what its functions are.

  1. Check the generator's wiring and connections to ensure they are secure and properly connected.

  1. Perform a visual inspection of the control module to look for any obvious signs of damage, such as cracked or broken components or loose connections.

  1. Check the generator's fuel system, including the fuel tank, fuel lines, and filters, to ensure they are functioning correctly and not causing any issues.

  1. Check the generator's air intake system, including the air filter and air intake ducts, to ensure sufficient airflow to the engine.

  1. Check the generator's exhaust system to ensure it is functioning correctly and not causing any issues.

  1. If the generator still does not function appropriately after performing these checks, it may be necessary to remove the control module and test it using specialized equipment. It is a complex process that a qualified repair technician should only perform.

Overall, the key to troubleshooting a diesel engine generator's control module is to carefully diagnose the problem and take the appropriate steps to fix it. It is essential to follow the manufacturer's instructions and consult a qualified repair technician to ensure you repair the generator correctly and safely.

How to replace a diesel engine generator's control module 

Troubleshooting and replacing a diesel engine generator's control module can be a complex task that should only be performed by a trained professional. If you believe that the control module on your diesel generator is faulty, the first step is to consult the owner's manual to see if it provides any guidance on troubleshooting the issue. If the manual does not give any helpful information, the next step would be to contact the generator manufacturer to see if they can assist.

If the control module on your diesel generator is faulty, you will need to replace it with a new one. To do this, you will need to follow these steps:

  1. Please disconnect the power source to ensure it is safe to work on the generator.

  1. Remove the cover from the control panel to access the control module. It may require the use of a screwdriver or other tool.

  1. Locate the control module and carefully disconnect any wires or cables.

  1. Remove the mounting screws or bolts that hold the control module in place and carefully remove the module from the generator.

  1. Install the new control module in the exact location as the old one, ensuring it is secured with the mounting screws or bolts.

  1. Reconnect any wires or cables disconnected from the old control module, making sure to connect them to the correct terminals on the new module.

  1. Replace the cover on the control panel and reconnect the power source to the generator.

  1. Test the generator to ensure it operates correctly with the new control module.

It is important to note that if you are not confident in your ability to safely and adequately replace the control module on your diesel generator, you should contact a trained professional to do the work for you. Attempting to replace the control module without the proper knowledge and experience can result in injury or damage to the generator.

You may want to know how to start a diesel engine generator.


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