That may be the wrong subject heading but let me explain what I am trying to do.
I have a circuit board that runs a set of lights in a certain sequence. I need to turn that board on which is powered by a jumper on that board.
How can I turn on that light board that is powered by the 2 pin jumper? If I plug it in to my bread board it will just turn on, I want to use my Arduino to jumper that connection.
Thanks
Josh
We need to know how the jumper is connected on the board.
It could switch on 5v, or it could switch ground. It could also do it some other unknown way.
A circuit would help.
Weedpharma
And a photo can be useful...
I have a circuit board that runs a set of lights in a certain sequence. I need to turn that board on which is powered by a jumper on that board.
How can I turn on that light board that is powered by the 2 pin jumper? If I plug it in to my bread board it will just turn on, I want to use my Arduino to jumper that connection.
This means absolutely nothing.
1- Post a schematic
2- What the hell is a 2-pin jumper ? What board ? What lights ?
I want to use my Arduino to jumper that connection.
This probably the only thing you said that makes any sense but it needs to be translated from non-electronics layman lingo to proper electronics nomenclature;
"How do I use an arduino to control an SPST RELAY ?"
I am using a arduino to control a servo and I want to also control a light board that run a certain sequence. That board has a jumper to turn it on and off and I am attempting to control that with my arduino. However I am not able to control the jumper connection.
Because every time I connect the sound board it completes the circuit thus turning on the board. Is there a way to control the jumper with my arduino?
Read the sticky post at the top of the forum that tells you how to post a query here.
Once you've done that and reposted correctly, someone may be able to answer you.
We're not mind readers.
Take a look at using a transistor configured as "open collector" wiki. This is the normal way to create a "switch".
Also look in this section of the forum for Arduino Basic Connections which shows how to connect almost anything to an Arduino.
Mark
Henry_Best:
Read the sticky post at the top of the forum that tells you how to post a query here. Once you've done that and reposted correctly, someone may be able to answer you. We're not mind readers.
MontgomeryFett:
I am using a Arduino to control a servo and I want to also control a light board that run a certain sequence. That board has a jumper to turn it on and off and I am attempting to control that with my Arduino. However I am not able to control the jumper connection.
There is an essential concept that you are not comprehending in your questions.
"That board has a jumper" ... is essentially meaningless in this context. 
Yes, the board has a jumper, but so do thousands (to say the least) of other boards. A generic "jumper" tells us exactly nothing.
Only when you show us the circuit of that board, or a link to the datasheet of that board, or enough perfectly focussed photographs of that board, whether on a commercial website, or a blog or you have taken them yourself, can we determine how it would need to be connected to an Arduino and what extra components might be required to do so.
And did I not mention - show us each part that you intend to use. No secrets!
This appears to be the same as your question in General Electronics.
Please do not cross post.
Weedpharma
Do not cross-post. Threads merged.
Without reading too much between the lines, it would appear that we can summarize the OP's request to simply :
"How do I use the arduino to connect two points electrically ? (assuming the OP knows how to make a female header cable to plug into the 2-pin male header "jumper" on the mysterious unknown board.
I suggested a small relay, but Holmes4's recommendation of an open collector transistor is probably going to be easier for the OP. I don't think we really need any more information but a photo of the jumper would be helpful. I think it's unrealistic to think we are going to see a schematic.
Hi
I would go for the relay option.
Do we know what is being switched?
An input to gnd?
An input to Vcc?
A multiplexed switch?
Tom.... 
TomGeorge:
Hi
I would go for the relay option.Do we know what is being switched?
An input to gnd?
An input to Vcc?
A multiplexed switch?
AC or DC?
What voltage?
What current?
The OP appears to want to keep the details secret and my crystal ball has crashed again.
Suffice it to say, the intel is poor and almost non- existant.
raschemmel:
I don't think we really need any more information ...
I disagree.
I think we need all the information I requested. As we always do. As Mr. Best also feels.
And the OP has gone to ground.
I think we need all the information I requested. As we always do. As Mr. Best also
feels
And the OP has gone to ground.
I suppose that makes it academic..
For what it's worth, I did say a photo of the jumper would be nice... 
Hello Everyone... here is what I am trying to do.
Sorry for the shaky camera and the wrong terminology that I am certainly using!
I don't know how to tell you this, so I'll just come right out and say it:
You need to ohm out that board and reverse engineer it to generate a schematic (I assume you don't have a link to a vendor for the board because I can't believe that you would have the bad judgement to post here on the forum without posting a link to the light board. That being the case, you need to get a pen and paper and draw a proper schematic and take a photo of it with your cell phone and post the photo. Until you post such a schematic , you will not get any help. If you had even the most basic experience in electronics you would have stated your request more specifically.
ie:
photo of block diagram showing jumpers
schematic symbol of switches shorting the jumpers
block diagram of arduino controlling the switches (perhaps using relays, or transistors)
etc etc etc
Sorry to say, but your video tells us nothing more than I already stated in one of my previous posts in this thread and which others have made similar , though different suggestions as a solution. There is nothing difficult about your question but as already stated, we need something more specific, like a schematic. If you actually are in possession of that light board , why have you not taken a close up photo directly above it (both sides) and posted these photos ? The only real mystery here is how you think we can help you without the details we need. (about the light board) or do we really need to know anything at all about the light board ?
If it were as simple as your video makes it sound, why would you waste time even talking about the motor or the light board and not simply ask:
"How can I use an arduino to close two SPST switches to short two 2-pin jumpers ?"
You are playing around with electronics. We need to know if you know anything about electronics so we know how to communicate with you. An SPST switch is one of the most basic concepts of electronics. The fact that there is no mention of this simple component in your request really suggests that you did not know the name of the component that you are asking for.
ie:
"I have two jumpers" (well, I'm calling them that but they aren't really 2-pin male headers as the term "jumper" would suggest. They are actually just two pieces of hookup wire sticking out of the bottom of my pcb"
"I want to short them with SPST switches/relays controlled by a uP (arduino)"
"The purpose is to replace two momentary switches (push buttons) with uP controlled contacts"
"I don't want to bore you with the reason i need to do this since it is irrelevant to my request"
"If I can control these two SPST switches/relays/transistors/optos with the arduino that will solve my problem (at the moment)"
Does that about sum it up ?
Also, you might clarify if the "jumpers" are actually factory made "jumpers" (2-pin male headers)(you do know what a male header is do you not ?) , or if they are not really "jumpers" (by definition) but simply pieces of wire sticking out of the bottom of the pcb that you have chosen to call "jumpers". This was not clear from the video.
I don't think we really need to know about the light board but if we do please post photos of both sides of the light board .
Please explain what you mean by "I don't really have anything to make a schematic ...etc"
Does this mean you don't have a pen and a blank piece of printer paper and a cell phone with a camera ?
or
does it mean you don't know how to draw a schematic ?
I think these are fair questions.
Seriously, am I being too harsh here ?
A relay is the safest choice for shorting unknown pins, but not the simplest.
Next comes an optocoupler, which requires a DC voltage drop across the open jumper - measure the voltage and current?
With a stable DC voltage, preferably full Vcc swing but not more, and a moderate (<10mA) short current, a digital output may be usable. Measure whether one pin is connected directly to either Gnd or Vcc, and if so, the other pin is the candidate for connection to the digital output. Good luck
Thanks DrDittrich,
I am just trying to short those two pins on the light board to activate it. I figured this would be something an arduino could do easily and I have probably confused everyone with just partial information, for that I am sorry.