LCD Displaying different characters

Good day..!!

We have our design project. My circuit uses a pump to produce steam. So when the pump is ob, water will flow and then go to the heater to produce steam. The problem is whenever the pump is on, the lcd display different characters and it only happens when the pump is turn on.

I try disconnecting the pump and there is no problem. I hope you can help in this problem. I tried different solutions I can think off but its not working.

My LCD is the Generic 20x4 LCD and my pump is the one you use in the aquarium.

The pump is probably not the problem, but the way you are driving it probably is. It sounds like you might be driving the pump directly when you you should be using a relay.

I'm using a 6V SPDT relay to drive the pump

Well, I did say "sounds like", but there are relays and there are relays, and some draw more than the 20mA available on an Arduino pin. Yours does not sound as if it was made with Arduino in mind, and the fact that LCD is fine when it is disconnected rather suggests that using that particular relay is a bad idea.

This all assumes that the power supply to Arduino is kosher in the first place. The problem could be there instead, and the relay merely reveals it. In that event, I would suggest you have two problems, both power, one at each end.

only happens when the pump is turn on.

Please clarify
when the pump is first turned on

or when the pump is running.

Does the processor resets or just goes " brown out" ?
Can you tell ??

Smaller voltage relays CAN take few hundred mA on turn on and most wallwart power supplies are not build for that.

Try searching this forum (use the stealthy search box at the upper right) for terms like LCD weird characters or LCD strange characters etc.

Don