Simulating a 0 volt button press

[Fozzie61]

I have an external circuit board with a button attached to it by 2 wires. I want to press the button via the Arduino. I cut the button out leaving me with two wires. When I touch them together it is the same as pressing the button. Okay, all very straight forward so far.

When I put one wire on the red terminal of my multimeter and the other on the black, it shows 5v. When I touch the wires together (simulated button press), the voltage drops to 0.

This should be simple but I've had a frustrating evening. How in the heck do I wire this up so my Arduino can make these wires "touch" and drop that to 0 volts?

[Franklin97355]

If one of the wires is at ground potential 0v to ground or short with a multimeter resistance scale. hook that to the arduino ground and the other to a digital pin through a 270 ohm resistor. When you set the pin LOW it should act as a button press.

[Fozzie61]

Thank you very much! That's what I was doing but I didn't have the resistor in the mix. It made all the difference in the world. Works perfectly!