Well hello again!! Let me summarize the situtation. I am using arduino mega 2560 and a 4-channel relay. I have a 5v two wired fan and a 5v two wired mini water pump. I am using different 6V batteries for each of them.
Here comes the problem: I made their connections the same way. And 5V two wired fan is working without a problem with my code. So, my code and my wiring is correct. But i am using the same wiring as fan and also same code with only changing the pin. And if i don't connect the last wire, i mean any wire about pump, not only red wire, to my breadboard i can see the relay is working as expected. The led of that channel, 4th channel turns on and i hear the clicking sound. However, when i connect the last wire about pump, it goes crazy. By crazy, i mean that, channel 4th's led starts blinking repeatedly and quickly, and pump doesn't work.
There is not a problem with the battery i use or wires i use. Because when i connect the pump directly to 6v battery, my pump works just well. And as i told, my wiring is also fine, because it works with fan. So, why my fan works greatly without a problem, but my pump doesnt work even though everything is exactly same?? Is there something special about water pumps, like i need to put a resistor or something?
Thanks in advance!!