I'm looking for advice. I pulled my Mindstorms 8547 kit out of storage and started to play with it after several years of inactivity.

I found that the Color Sensor, the Ultra Sonic Sensor, and the position read back on motors all do not function. I downloaded the latest software and firmware version 1.31.

Any idea what is going on? Do I need to go back to a previous firmware version to get things to work as they did originally?

Any advice is appreciated, thank you.

  • Is there any chance it's simply your code that isn't working? Could you add a screenshot of the program you're using to test the functions?
    – MindS1
    Nov 27, 2018 at 1:40
  • Using the "View" directly from the NXT brick to test the sensors, just get all ?????on the display with the color or ultrasonic sensor plugged in.
    – Paul
    Nov 28, 2018 at 22:34

2 Answers 2


Check for 5V on the two middle pins of the motor connectors (plug a cable into the brick, no motor on the other end, and measure volatege on the contacts of the open other end). NXT/EV3 have separate power to all the sensors, if there's a short (failed capacitor or similar) or the power chip failed then the brick will still work, but the sensors won't get power.


This honestly just sounds like a faulty cable. See the NXT cable pinout below. If wire 5 or 6 is damaged it will cause digital I2C sensors to fail. This includes the color and ultrasonic sensors, but not the (analog) touch sensors.

Also, according to this source, pin 5 and 6 are also used for the motor encoders. So damage to 5 or 6 will cause rotation feedback to fail.

This sounds exactly like the issues you are having. The solution? Try a different cable to confirm that the issue is a faulty wire, then (optionally) buy new cables from here.

NXT Wire Pinout

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