Based on the answer here it seems that resistors are used to detect what is plugged in with LEGO Power Functions 2.0. So which resistor values (or ranges) apply to which motors or other devices? Are there any values of resistance that lead to "unknown device" errors or something like that?

1 Answer 1


M Motor (Powered Up/WeDo 2.0)

The M motor has a 2.2kΩ resistor between pins 5 and 6. Pin 6 is connected directly to pin 3.

M motor

LED Lights

I don't own any lights yet, but according to this post, they also use a 2.2kΩ resistor, but in this case it is between pins 5 and 3. This pulls ID 1 to ground. Here's the full circuit diagram:

LED light circuit diagram

Train motor

The measured resistance between pins 5 and 6 shows an open circuit. Pin 5 is connected directly to VCC, and pin 6 is connected directly to ground.

train motor

Other components

I wasn't able to determine any sort of passive identification on any other components (Boost motor and sensors, etc). My guess is that these have an onboard microcontroller and use an active handshake before establishing a data connection.


M Motor
3 (GND) ─────┐
4 (VCC)      │
5 (ID1) ─2.2k┤
6 (ID2) ─────┘

LED Lights
3 (GND) ─────┐
4 (VCC)      │
5 (ID1) ─2.2k┘ 
6 (ID2)

Train Motor
3 (GND) ───┐
4 (VCC) ─┐ │
5 (ID1) ─┘ │
6 (ID2) ───┘
  • Thanks Still wondering if the WeDo 2.0 motor works on 3v or 9v. Not sure what would happen if you plugged a WeDo motor into the Train or Boost Controller. Possibly the WeDo has a DC-DC converter to up the 3v to 9 v for the motors. This may also explain why the batteries on the WeDo 2.0 do not last very long, about 2 - 3 class room use.
    – Ddodge40
    Commented Sep 23, 2018 at 20:39
  • I believe WeDo 2.0 steps up the voltage to 5v (philohome.com/wedo2reverse/cont.htm). Motor power scales with voltage, so the exact voltage used is variable. You can use the WeDo 2.0 motors with the Powered Up hub. This is what powers the Batmobile.
    – jncraton
    Commented Sep 23, 2018 at 21:34

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