How to configure RCEXL – Opto Ignition Cut Off Switch

It’s crucial to understand the importance of Ignition cutoff switches. They are an essential component for any RC airplane powered by a gas engine. By integrating an Ignition cutoff switch into your aircraft, you gain the ability to securely and remotely turn off the engine by merely toggling a switch on your transmitter.

This switch serves as an essential safety feature that, ideally, will never be required by the user. However, in the unlikely event that you need to quickly stop the engine, aside from crashing the plane, having this switch in place is highly beneficial.

It is considered one of the most effective insurance measures you can implement on your plane, ensuring that you have complete control over shutting down the engine whenever necessary. The RCEXL Opto Gas Engine Kill Switch is widely recognized as one of the most popular options available. Upon examining the switch’s image, you will observe that it is equipped with only three cable connectors: the receiver cable, ignition cable, and battery cable connectors.


  1. Plugs into a spare receiver channel.
  2. Includes a remote mountable bright red LED to indicate when the ignition is armed
  3. Fiber optic coupled input/output
  4. Li-Po/Li-Ion/A123/Ni-n/Ni-Cad input
  5. Low voltage drop – less than 150mv
  6. 100% surface mount technology
  7. Heavy gauge wires
  8. Universal connectors
  9. Small and light weight – 0.3 oz (8 grams)
  10. Reverse battery input protection
  11. Turning off transmitter or received power will automatically kill the engine
  12. Allows for safe termination of the engine at any time – ground or air borne

Step-by-Step Guide: Attaching an Ignition Cut Off Switch to an RCEXL Ignition Module

  1. Identify the cables on the ignition module – On newer RCEXL ignition modules, you will notice four cables running from the unit, while older units have only three.
  2. Locate the battery (Power in) connector – Connect the ignition cutoff switch to the ignition module by attaching it to the battery (Power in) connector. This cable acts as the conduit to supply power to the ignition unit.
  3. Understand the purpose of the Opto ignition cut off unit – Without the Opto ignition cut off unit, the ignition battery would directly connect to the ignition module.
  4. Connect the ignition battery to the cut off switch – Attach the ignition battery to the cut off switch, enabling it to control the power supply.
  5. Connect the cut off switch to the receiver – Use another cable to connect the final connector from the cut off switch to the receiver. Ensure that you select an unused receiver port, such as aux 1, aux 2, gear, etc., for the unit to operate correctly.
  6. Verify the physical connections – Once the above connections are made, the physical work is complete. Note that the LED (not shown in the diagram) must be mounted in a noticeable location on the plane for the user to see.
  7. Check the LED indicator – When the ignition cut off switch is functioning properly and connected correctly, the LED will emit a red glow. This indicates that the unit is live, armed, and supplying power to the ignition module. If the LED is not glowing red, there is no power being delivered to the ignition module, and your engine will not start.
  8. Ensure proper functionality of the transmitter switch – On your transmitter, verify that the switch responsible for controlling the cut off switch is operating correctly. Most, if not all, issues with non-operational switches can be identified at this stage.

By following these step-by-step instructions, you can successfully attach an Ignition Cut Off Switch to an RCEXL Ignition Module, ensuring proper power control and functionality for your RC airplane.

Important Notes:

  1. Toggle switch assignment: Determine which toggle switch on your transmitter is assigned to work with the cut off switch. This will ensure proper control over the ignition cut off function.
  2. Maximum throws assignment: In the programming function of the transmitter, make sure to assign maximum throws to the cut off switch. If the throws are too narrow, the cut off unit will not function properly. Throws are typically assigned as a percentage function in transmitters. Verify that they are set to their maximum value for optimal performance of the cut off switch.
  3. Correct connector installation: Ensure that the cut off switch connector is installed correctly in the receiver, with the black wire connected to the black terminal and the red wire connected to the red terminal. Proper wiring ensures the effective operation of the cut off switch.
  4. Check receiver port pins: Verify that the pins in the receiver port being used by the cut off switch are straight and not bent or broken off. Damaged pins can hinder the proper functioning of the switch, so it’s important to ensure their integrity.

These important notes address crucial considerations to ensure the smooth operation and functionality of the cut off switch in your RC airplane system.