Generator Runs But Won't Transfer Power
The engine is running, the panel shows no fault, and the house is still dark. This is one of the more frustrating standby-generator problems because the generator itself is usually fine — the break is almost always in the automatic transfer switch (ATS) that's supposed to move the house load onto it.
What this looks like
A correctly working standby setup does three things during an outage: the generator starts, the ATS senses utility power is gone and disconnects the house from it, then the ATS connects the house to the running generator. When you're stuck with "runs but won't transfer," step one worked and steps two or three didn't. You'll typically see the generator's own display or LED reporting no fault at all — Generac's Evolution/Nexus panel will just show it running normally, Kohler's RDC2/DC2 the same, and a Briggs & Stratton unit's single LED stays dark or solid rather than blinking a code. That's the tell: the generator has nothing to report because, from its point of view, it did its job. The transfer switch is a separate piece of equipment with its own enclosure, its own fuse, and often its own small indicator light, and that's where this fault actually lives.
Most likely causes, ranked
- Transfer switch left in the wrong position. Most ATS units have an AUTO/MANUAL/OFF (or similar) selector; if it got bumped to MANUAL or OFF during maintenance, testing, or a previous outage, it won't transfer automatically no matter what the generator does.
- Blown fuse inside the transfer switch. Briggs & Stratton's own Home Generator System documentation calls this out directly as its most common transfer-switch failure, and it's plausible on any brand's ATS since most use a small internal control fuse.
- Damaged or loose control wiring between the generator and the transfer switch. The ATS needs a signal from the generator confirming it's up and stable before it will switch; a chewed, corroded, or disconnected control cable breaks that handshake even though the engine runs fine.
- Utility power isn't actually fully gone, per the ATS's sensing logic. A partial outage, a single blown fuse on the utility side, or a neighbor-shared transformer issue can leave just enough voltage present that the switch's logic doesn't call it a true outage.
- Managed or load-shed transfer switch misconfigured. Some Generac systems pair the generator with a switch that manages which circuits get power and in what order; a misconfigured load-management setup can leave circuits unpowered even after a successful transfer.
Which fault codes match this
Of the three brands documented on this site, only Briggs & Stratton's Home Generator System has a distinct fault code specifically for the transfer switch itself. Generac and Kohler ATS problems generally show up on the transfer switch's own indicator light, not as a code on the generator's panel — which is exactly why this symptom can look like "nothing is wrong" from the generator's side.
| Brand | Code / display | What it confirms |
|---|---|---|
| Briggs & Stratton | FC_8 (8 blinks) | Fault in transfer switch communication or operation, most often a blown internal fuse |
| Generac | 2100 (Overload) | Not an ATS fault itself, but a managed transfer switch's load settings can trigger this if too many circuits transfer at once |
What you can check yourself
- Confirm the generator's own display genuinely shows no fault — if it does show a code, you're dealing with a different problem and should look that code up instead.
- Check the transfer switch's selector position; it should be set to AUTO for the system to switch on its own during an outage.
- With the enclosure cover on and no tools involved, look for an obvious indicator light on the ATS itself showing power or fault status, per its manual.
- Verify the main breaker at the house panel that feeds the transfer switch hasn't been shut off for unrelated work.
- If you know the transfer switch model, check whether it's a managed/load-shed type and whether its configuration matches your home's actual circuit demand.
More help
If your generator's display is actually showing a fault, the code lookup will get you to the right page faster than this one. Otherwise see the full code lists: Generac, Kohler, or Briggs & Stratton.