Water pump as output

Using Arduino LEDs and Multiplexing
1

Hello I am in deep need of help, I have a keypad 4x4 matrix as input where as you enter a 4 digit number a certain output follows(water pump in my case), so basically i tried the circuit with a LED and it worked just fine, but without changing anything in the circuit only replacing the LED with the water pump makes the water pump not operate although the water pump operates using the 5v power pin , what makes it not work even though the LED works in the exact same situation in the circuit? Idk how can I draw the circuit for you here but I hope my information is enough, I have stated it worked just fine as I wanted it to work but the difference is that it worked fine using a LED as output but replacing the output without moving any circuit components just literally makes the water pump not work.

PS: It's just that the digital pins seem to not operate it although they output a 5v same as the power pins.

What I use(if it makes any difference):
4x4 matrix keypad
Arduino UNO
5v water pump

2

Hi, and welcome to the forum.

An Arduino output pin can't provide the current to power a water pump.
The 5volt supply pin shouldn't even be used to power a pump, unless it's a tiny one.

20mA (a LED with curent limiting resistor) is about the maximum an output pin can safely handle.

If you want to switch more than that, an external power transistor is needed.
Post the details of the pump (voltage, current) for the right circuit.

This circuit could be used to control a powerful 12volt pump.
Leo..