Generac Guardian C6211 6211 Generator Controller Reverse Engineer Schematic Wiring Diagram

[k6xtc]

I have a Generac Guardian 04390-2 15KW (LP) Home Standby Generator.

It is an older model with only status LEDs and no Internet connectivity or any way to monitor the system.

It was having issues and not starting. It looked like a problem with the controller but replacing it didn't fix the issue. I finally traced it to bad contacts in the rocker switch. I learned a lot about the workings of the generator in the process and though that it shouldn't be that hard to roll my own controller with data logging and remote control.

So I decided to see if I could design a replacement using an ESP-32 development board. The idea is to design a custom controller board that is a direct fit for the original. It will use the same size board, same mounting hole spacing and most importantly, the same connectors so there is no need to modify any of the wiring in the genset.

My first step is to reverse engineer the stock controller.

IMG_5720.jpg

As it is a working board I did not want to remove any components. Fortunately it's only two layers so most of it was easy to capture. Other than removing the relays I was able to keep it intact.

In case you're wondering about the bolts; They are there so the board will sit level when photographing the bottom side.

[k6xtc]

Generac C6211 Rev-A Controller Pinout

Generator Controller Pinout.pdf

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Generac C6211 Rev-A Controller Parts List

Generator Controller Part List.pdf

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Generac C6211 Rev-A Controller Graphics in GIMP file format.

multiple layers showing pads, vias, traces, groundplane and components.

Controller-2.xcf

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Generac C6211 Rev A Controller Schematic

Generac C6211 Rev-A Controller Schematic.pdf

[k6xtc]

Updated schematic.

Found and fixed a few errors.

Split into sub circuits by function.

stock generator controller 2.pdf