Generac Generator Troubleshooting, Help, and Repair Forum | Gentek Power

Hello all. This forum is looking like my last hope with this. Here's the information
Model: G0070400
S/N: 3001613430
Production Date: 20170329
Controller: 0K7497C

The problem: It fails to run on about 80% of power fails, emitting Error Code 1062.

Known good:
Gas supply is nominal 11WC and of sufficient capacity.
AC and control wiring are known correct and of correct wire sizing.
Engine and its speed control work perfectly. Any failure to run is caused by controller-commanded shutdown.
When it runs under varying loads the speed/frequency control works as intended 100%.
Exercising always works correctly.

Repair attempts so far: Controller and VSFC module have both been replaced twice, with no effect on behavior. MANY visits from "Authorized Repair Techs" with no resolution.

Symptoms:
If there's no error code showing (or has been cleared) AND utility power is present, it will start and run correctly 100%.
If utility power fails, 80% of the time it will crank and stop, asserting Error Code 1062. This code cannot be cleared. On utility restoration, the code cannot be cleared immediately, but after a few hours on utility power it WILL clear.
When it was first installed it failed to run on the very first attempt, asserting Error Code 1062.
The house load is very light. Capacity is not an issue. Normal load is typically under 2KW. It has run fine supporting two 4-ton ACs.
On those 20% of occasions when it DOES start on utility fail, it will bog and stall on load transfer, asserting Error Codes 1063 and/or 1064. Restarting and waiting about a minute to transfer the load generally avoids these two errors, even though it still bogs heavily.
Every once in a blue moon it will work perfectly on utility fail. (We have a LOT of utility problems here, averaging an outage about every three weeks.) This (rare) start/transfer sequence has occurred maybe 4 times in its life.

Other oddities:
The waveform is rather dirty. Even when supporting the load normally, there is frequency instability of about +- 0.5 Hz. as set from the factory, the output voltage was too low. I was able to trim it up to nominal, but that trim setting was below the recommended range. It's currently set to deliver about 118VAC.
There's a voltage instability that's especially visible on LED lighting that's on dimmers. However, it can sometimes be seen even on non-dimmed LEDs.
The two legs are never balanced, even on nearly equal loads. They differ by 1 to 2 volts.

Generac has been of minimal help. They don't pay their "authorized dealers" for a service call unless they fix something. Well, the techs here are unable to diagnose this. Generac has essentially washed their hands of my unit at this point. It's a lemon, obviously, but they just don't care.

Thanks for reading. Even more thanks for assistance.

Well, let's start with what the error is really about.

Error code 1062 VSCF Comms Loss is basically the controller telling you that it has lost communication with the AVR (voltage regulator). They use a shielded cable (among other cables) to talk back and forth which is unique to the Synergy models. There can be a multitude of reasons why this loss occurs, but a few are listed below:

The cable itself is faulty, loose pin, miswired, etc.
The cable is incorrectly shielded, meaning the shield inside is grounded improperly.
The AVR isn't on, or has no power. The green LED should be lit
The controller is damaged (you've had 2 so lets not assume that)
The firmware was corrupt, an update should be done regardless to make sure it's not a software issue.

These communication lines can be tested with a DMM (digital multi-meter). Not sure how much training the other techs have, but these units are rare and parts are INCREDIBLY expensive for them! The AVR alone lists for almost $3100.00

Hi Chris. Thanks for the reply. I sort of knew all that already since it's in the service manual 0K9138. But none of these account for the weird behavior, for example, why it will start when utility is present, but as soon as utility disappears it emits 1062. If I start it manually (and wait a minute) and then kill the utility, it always transfers normally without any errors. This suggests (just spitballing here) that the VSFC gets power as long as the utility is available, but is unable to draw from the battery. Seems pretty farfetched to me, but then... Even weirder, once 1062 is asserted, it will remain for several hours after utility restoration, and then become clearable. I agree that wiring or connectors are highly suspect.

Here's another question you can probably shed some light on: I specified an AGM battery. It seems to charge normally and maintains around 13.8 at the battery while charging and no-load. That looks pretty good. However, when I measure the +12 line inside the transfer switch I get only about 10.7V. That might be okay, but it seems odd to me. What do you think?

Just checked: there's a green light on the VSVC under load. When I have a chance, I'll cause a 1062 error and see what it shows.

The 10.7V you're seeing at the transfer switch is probably a little voltage drop over the wiring to the switch. What size wiring was used, and how far is the run to the transfer switch from the generator?

I agree that the symptoms are quite strange and I'll admit that my knowledge of the Synergy inner workings is also somewhat limited since I've only got 1 of them there that I work on.

The AVR and Evolution controller are all 12V, so there's no utility power involved when it comes to running those components. Really the only utility power to the unit would be for the charger and for the utility sensing circuit to tell the generator when to run.

It almost makes me wonder if the battery voltage is dropping off when the charger shuts off?

It looks like 18ga signal & 12V power wiring. Length is, maybe 15' tops. That would have to be a heck of a lot of current to cause a 2V drop. There's nothing in the transfer switch that could be drawing that much. I don't think the battery is the problem since the 10.7V is fairly constant no matter what the generator is doing. Does a Guardian Series have the full battery voltage at the transfer switch? The controller reports the battery condition as "good".

I've been through the service manual a few times and haven't been able to find any spec on the DC voltage anywhere. Do you have a Generac spec on what it should be in the transfer switch? What do you see in a Guardian?

Also, it looks like the "communication" between the VSVC and Evolution controller occurs over a RS485 link. https://en.wikipedia.org/wiki/RS-485. There's nothing in the manual about that at all. I don't even see the connector for it. Where do you suppose it is? I have a feeling that the problem might be nothing more than a flaky wire assembly or connector.

Well, a good test for the 194 voltage would be to measure it at the generator's control terminal strip and compare. Low voltage DC drops QUICK with a small amount of current and small wire. Usually there is some voltage drop, and as long as you're getting enough to pull the contact in inside the transfer relay, you're fine. Now, that being said, if the entire generator is seeing 10.7V through the control system, sensors, etc, that may explain some things....

There are a few mentions of the RS485 signal in the diagnostic manual, also called the 'communications link'. Pg. 147 has a good walk-through on what happens when the unit first starts. See page 119-120 for information about diagnostics for the RS485 comms.

Looks like I have a "solution", though it's not likely addressing the actual problem: The generator starts & runs normally if you hold up the battery charger connection to the "load side" in the transfer switch. IOW, I put a small UPS at the transfer switch to power the T1 connection so it stays energized at all times, including during the period between utility loss and generator coming online.

There's something fishy going on here because there's a statement in the DRM that claims that the controller (and presumably the AVR) gets its DC supply "from the battery charger", implying that if there's no power to the charger, they might not get power. So what are they supposed to do during a charger-deenergized condition? Obviously, at least in my generator, it's necessary that the charger remain powered. I see nothing in any of the various wiring diagrams that offers a clue to this nor does it make any sense to design it this way.

Unfortunately, without schematics of the controller and AVR this is probably going to remained less than fully solved.

That would be a strange set of circumstances because all standby generators lose charger power momentarily during the outage until the generator comes online and re-powers the charger circuit. I personally don't have enough experience with the Synergy models to know exactly how their controllers react to certain circumstances, however I've not heard of anyone else having this issue either... I don't have internal schematics for the controllers or AVRs, as I'm sure you know, that information is guarded by the manufacturer.