Understanding Indicator Lights - IQ Controller (1st gen)

Using VEX IQ (2nd generation)? See this article.

Notice there are two different indicator lights on the Controller. The first indicator light is called the Power / Radio Link LED.

There are two possible colors of the Power / Radio Link LED to indicate the status of the VEX IQ Controller Battery and of the VEX IQ Radio Link:

Power / Radio Link LED Color   Status

Diagram of the VEX IQ Controller, illustrating its buttons, joystick, and connection ports, designed to assist users in understanding the controller's layout and functionality for educational robotics projects.

Solid Green Controller ON - Controller Battery level sufficient - with NO Radio Link (searching)

Diagram of the VEX IQ Controller showing its buttons, joystick, and layout, illustrating key features and functions for programming and operating VEX IQ robots.

Blinking Green Controller ON - Controller Battery level sufficient - with good Radio Link.

Image of the VEX IQ Controller, showcasing its buttons and layout, used for programming and controlling VEX IQ robots in educational settings and competitions.

Solid Red Controller Battery level low - with No Radio Link

Image of the VEX IQ Controller, showcasing its buttons and layout, designed for educational robotics use. This controller is part of the VEX IQ Robotics platform, aimed at beginners and educators for programming and building robots.

Blinking Red Controller Battery level low - with good Radio Link

If the Controller’s LED is not blinking, the Controller is not wirelessly connected to the VEX IQ Robot Brain. Connecting with the Tether Cable overrides the wireless connection and the Controller’s LED will show solid green. Click here for instructions for properly linking (wirelessly connecting) the Controller with the Brain.

The second is called the Charge LED. 

Image of the VEX IQ Controller, showcasing its layout and buttons, used for programming and controlling VEX IQ robots in educational settings and competitions.

There are three possible colors for the Charge LED: green, red, and gray.

Charge LED Color   Status

Diagram of the VEX IQ Controller, illustrating its buttons, joystick, and connection ports, designed to assist users in understanding the controller's layout and functionality for educational robotics projects.

Solid Green Controller Battery is completely charged

Image of the VEX IQ Controller, showcasing its buttons and layout, used for programming and controlling VEX IQ robots in educational settings and competitions.

Solid Red Controller Battery charge in progress

Image of the VEX IQ Controller, showcasing its buttons and layout, designed for educational robotics use. This controller is part of the VEX IQ Robotics platform, aimed at beginners and educators for programming and building robots.

Blinking Red Controller Battery fault

Image of the VEX IQ Controller, showcasing its buttons and joystick layout, designed for educational robotics, enabling users to program and control VEX IQ robots effectively.

Off Not charging

Click here for instructions for charging the Controller Battery.


Indicator Lights when Wirelessly Connecting

When wirelessly connecting a VEX IQ Controller to the VEX IQ Robot Brain, the indicator lights on the front of both the Controller and the Brain may display different colors. The different lights and flashing patterns indicate the status of the Brain’s and Controller’s connectivity and power.

Image showing the VEX IQ Controller, highlighting its buttons and layout, designed for educational robotics. The controller is used in programming and operating VEX IQ robots, facilitating hands-on learning for students and beginners in robotics.

Use this checklist when testing connectivity and understanding indicator lights:

  • Is the Power/Link LED on the Controller and the Brain LED both solid green?
    • If the answer is Yes, then the devices are charged but not paired. 

Follow the instructions in How to Pair the VEX IQ Robot Brain with the VEX IQ Controller for Wireless Operation

  • Is the Power/Link LED on the Controller and the Brain LED both blinking green? 
    • If yes, then success! Both LEDs should blink green when wirelessly connected. 

It indicates that there is a good connection and both batteries are charged.   

    • Is one or both of the LEDs red or blinking red? 
      • If the answer is Yes and the Controller’s LED is red, then the Controller Battery is low. 

Follow the instructions in How to Charge the VEX IQ Controller Battery

    • If the answer is Yes and the Brain’s LED is red, then the Robot Battery is low. 

Follow the instructions in How to Charge the VEX IQ Robot Battery.  

If the wireless pairing is still unsuccessful, be sure that the VEX IQ Radios in the Brain and Controller are a matching pair. Review the following:

For more information, help, and tips, check out the many resources at VEX Professional Development Plus

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