I am trying to use the ATS (automatic transfer switch) interface of a generator to set up a remote start system using a microcontroller with a cell phone modem and relay bank (for a rural microgrid application in India).

The ATS interface connection is shown below:

enter image description here

In the circuit diagram, the five pins are labeled as follows. Based on the labels I'm inferring inputs vs outputs, and guessing at what GC and MC stand for.

INPUT?   1. Auto start switch
OUTPUT?  2. GC relay            generator contacter?
         3. MC relay            mains contacter?
         4. BAT+                12V lead acid battery
         5. BAT-

Can I use this interface to start the generator? If so, how, and what is each pin for? Also, what is this type of connection called, so I can order the appropriate cable?

The manual for the generator does not include any detail. However, it's my understanding that the 12V+/- supply power to the ATS, GC and MC are to allow the genset to drive contacters, and the auto start switch should short to ground to start the generator, then open circuit to stop it. Is this correct?

  • 2
    \$\begingroup\$ Call me ignorant, but what does "ATS" mean? \$\endgroup\$
    – dim
    Jul 21, 2016 at 12:51
  • \$\begingroup\$ My guess would be "Automatic Transfer Switch" -- and yes, this interface should be capable of starting the generator. \$\endgroup\$
    – Dave Tweed
    Jul 21, 2016 at 12:56
  • \$\begingroup\$ @dim sorry, not sure how I left that out. \$\endgroup\$
    – LShaver
    Jul 21, 2016 at 13:23
  • \$\begingroup\$ @DaveTweed , this much I know... my question is how to do it? what signals on what wires? \$\endgroup\$
    – LShaver
    Jul 21, 2016 at 13:23
  • \$\begingroup\$ Could you annotate the pins as "input" or "output" wrt the generator interface? \$\endgroup\$
    – scorpdaddy
    Jul 21, 2016 at 14:02

2 Answers 2


If it were me, I'd measure the voltage on pin 3. If there's 12 volts, I would try shorting it to ground through a 12V light bulb or equivalent (to limit the current) to see what happens.

  • \$\begingroup\$ That did it. By the way, I wasn't actually numbering the pins, just listing them. So your answer refers to pin three, which is "auto start switch." When I short this to BAT-, the generator comes on. Once I release it, the engine stops. \$\endgroup\$
    – LShaver
    Jul 22, 2016 at 13:36

pin1 bottom right posituve pin2 right starter motor pin3 top ac wave form pin4 egnition and fuel pump pin5 negitive earth

conect pins 1 to pin 4 should switch on egnition a light should lightg up conect pin2 will start starter moter when started discinnect

to stop disconect pins 1 and 4? you will need 1 on/off switch and a push switch

PIN1 IS ONLY LIVE WHEN THE ORIGINAL SWITCH IS IN THE OFF POSISTION so you can use original to start it or remote when it off

  • 1
    \$\begingroup\$ We don't expect every answer to be perfect, but answers with correct spelling, punctuation, and grammar are easier to read. They also tend to get upvoted more frequently. Remember, you can always go back at any time and edit your answer to improve it. See Write to the best of your ability on the site's help pages. \$\endgroup\$
    – Transistor
    Jan 31, 2019 at 19:36

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