Dual Relay with Raspberry Pi Pico always on

I am working on my first project with a Pico W and a Sunfounder Dual Channel Relay. This is going to control 12V DC heating pads under lithium batteries. I only need one channel.

I have studied the wiki and believe I have this wired correctly. I am using a LED to test for power. A voltmeter shows about 3.3 volts on the VCC wire.

I assume the COM port supplies the power that is then switched on or off to the terminal to the right of it.

Regardless of the state of IN1 or IN2, power from COM always goes to the terminal to the right of COM. So it seems like both channels on the relay are always on.

The LED on the relay board comes on when the IN1 or IN2 is off. I do not hear a clicking sound when one of them is powered on.

Any ideas about what could be wrong would be appreciated.

Are you carrying out one of our kit projects? Or is it your own project.

  1. If it is our project, please tell us in detail what problems you encountered when running that class.
    Make sure the wiring is connected correctly.
    You mentioned 12V DC, I don’t quite understand what you mean.
  2. If it is your own project, please provide us with your code, and the wiring diagram of the project, so that we can help you reproduce the problem.

This is my project. I connected directly to the + and - on a breadboard and confirmed the wiring was good with a known working relay.

I have to conclude that the relays are both defective. NC is always on regardless of the IN status:

Sorry about the relay issue.
Please send us (support@sunfounder.com) your shipping address with phone#(just for shipping) and images of the defective relay.
We will send you a new relay.