My goal is to turn on an electric generator remotely. I have a SMS (text message) controlled circuit board that has 7 relays. I can control each relay independently. I want to send a text to essentially turn this generator that has a keyed, electric starter on it.

So, the first text should close a relay that allows energy to flow (ie. key in 'run' position). Second text will close a relay that initiates the starter for a few seconds (ie key to the 'start' position). The last text would interrupt the energy flow (ie key in off position) to stop the generator.

My question is: What wires do I need to use to allow energy flow ('run') and what wires to I need to use to initiate the starter ('start')? I have looked at the physical wiring and also the diagram but cannot figure it out. Before I do something that may harm things, I thought I'd post.

Below is the wiring diagram:

enter image description here

  • For clarification: I am going to power a water pump for irrigation from this generator. I won't be connecting it to a home or any other purpose.
    – macecase
    Feb 16, 2016 at 18:00
  • This looks like it's bordering on a hobby project, not sure how applicable it would be to others.
    – BMitch
    Feb 16, 2016 at 18:40
  • 2
    I would avoid doing this in this manner. Text message are subject to delays and out of order delivery, so you could end up doing rather bad things. If you want to do this, you really want to have a single text trigger a simple microcontroller to run the start procedure for you. Fortunately the answers to the question are still relevant in that case though. Feb 16, 2016 at 19:21
  • @BMitch, this is actually to power a drip irrigation pump that draws water from a creek. Generator Starts and powers an electric pump. That water goes through two 55 gallon drums filled with sand/stone to filter and then into a series of drip irrigation lines. In Kansas, I can irrigate a certain number of acres without a permit. So, I am doing this for my farm since I have a wide creek that borders it. I would argue that it may be helpful to others in terms of setup and usefulness.
    – macecase
    Feb 18, 2016 at 16:01

2 Answers 2


According to the schematic.

Generator start switch schematic

The unit is OFF, when IG and B are connected. To start the unit, connect ST and BAT. Once it's running, none of the contacts should be connected.

You're going to want to find a way to monitor the engine, so you know when it's running and can stop cranking the starter. You'll likely want to crank the starter in shortish intervals, rather than simply cranking until the engine starts. You'll want a way to stop cranking the starter after x number of tries, so you don't keep cranking an engine that won't start. You'll also need a lockout mechanism, so that the device cannot start the generator when somebody is working on it or the system.

As for connecting to the homes electrical system. You're going to want to use properly installed transfer equipment. And you're going to want to make sure the installation is code compliant.

Finally... If you're going to be working on projects like this, you're going to want to learn how to read schematics. It makes me slightly nervous that you're asking this question.

  • 1
    And he'll want to have interlocks that prevent this device from starting the generator when someone is working on it.
    – Johnny
    Feb 16, 2016 at 18:11
  • Ah, yes. Good point @Johnny.
    – Tester101
    Feb 16, 2016 at 18:22

The relay that is on a short "crank" timer can go from your +12V to the starter solenoid in parallel with the switch that way you could still start it by hand. I hope you are installing an automatic transfer switch for legal and safety reasons.

  • Can you elaborate notating wiring colors from the diagram?
    – macecase
    Feb 16, 2016 at 17:54
  • I am sorry I am doing this on my phone and cannot read the print. the starter has 2 wires going to it the big red wire from the + terminal on your battery and a small wire that engages the solenoid. the small wire is the one you need to put in parallel with a relay to the + battery connector to engage the starter.
    – Ed Beal
    Feb 16, 2016 at 19:53
  • You should really read the question " I hope you are installing an automatic transfer switch for legal and safety reasons." is not applicable here.
    – Sam
    Feb 16, 2016 at 23:28
  • 1
    He added the unit was for a pump quite some time after I put my answer up so I would hope you have the 00 to reverse the -
    – Ed Beal
    Feb 16, 2016 at 23:31

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