pinMode() automatically sets digital pin to high

[gfvalvo]

@DaveX

The “low level trigger” text with

@whernandez619

    digitalWrite(pins[i], LOW);
    // Initialize the relays to be off

makes me think that the solenoids might be attached to the NC terminals and the issue might be that NC contacts are closed on power up.

Another interesting possibility.

[westfw]

@DaveX

Module with Optocoupler

OTOH, I'd normally expect an optocoupler-based relay driver NOT to be subject to turning on with "floating inputs." It takes a somewhat substantial bit of current through the LED for an optocoupler to turn on.

[DaveX]

The Amazon pic looks pretty optocouplery:

[Wawa]

@whernandez619

Here is the relay board I am using.

It is indeed "active LOW", so you need to do what I said in post#13.

The worst relay board you can buy.
Opto couplers, but no opto isolation, because of a design fault.
The opto LEDs are permanently connected to the opto transistors (has no JD-VCC jumper).

There are also several versions of that board. With or without buck converter. If you hover over the first and second small image on the left of that web page, you will see.
So which one have you got. And how are you powering the board when it hasn't got a buck converter fitted. Does it have 5volt relays or 12volt relays fitted.
Leo..

[GoForSmoke]

Current above led forward V.