Connecting a motor forward/reverse controller board

I am new to Arduino and really enjoying starting learning something new. The picture shows a forward reverse controller board moving a linear actuator. I can move it forward and backward by shorting between the input pins of the controller board. How do you do this function of shorting between the pins of the controller board from an arduino? I have tried to do a quick output low followed by an output high but nothing happens. Interetingly If I remove the digitial return on the arduino and then replace it, it does work. It would be great to understand what pins and code I would need to replicate this. Thank you in advance

Well first we need to know more about your controller board.
Do you have a data sheet or a link to where you purchased it?

For now, do NOT connect it to your Arduino

Which Arduino are you using?

Hi Jim, thank you for your sppedy reply. This is the information I have on the device


and I am using a DFRobot Bluno Mega

Well, the problem is we don't know what the voltage is on the trigger pins. If it's higher than 5V it will damage your Mega.

Can you measure the voltage across the trigger pins?

It is about 6v

Then you will need a simple transistor circuit to trigger the relay.
Do you know how to read a schematic?
Do have any transistors or MOSFETS?

Hi there I have some transistors and will take a quick look online for a tutorial. Thank you so much for your time Jim it is appreciated.

If there was a particular circuit in mind that would be appreciated if you could point me in the right direction

If you tell me the part numbers, I'll tell you how to connect everything.

The NPN I have is a 2N3904

My relay module is different but just connect the wires to T and G as shown.
A HIGH on the Mega output pin will activate the relay.

Hi Jim, that works perfectly, thank you so much for taking the time to support me. I get a bit nervous about posting on a forum and you have been so kind

Have a nice day!