RV generator runs but there is no power in the coach
What this usually means
A generator is two machines bolted together: an engine and an alternator. If the engine runs correctly and no power reaches the coach, the engine half is proven good and the fault is on the output side — the generator’s own breaker, the alternator end, or the automatic transfer switch that selects between shore power and generator.
Check this first
Check the generator’s own circuit breaker, which is usually on the generator itself rather than in the coach panel. It is frequently overlooked, trips for ordinary reasons, and produces exactly this symptom.
Stop-work system
Generators combine fuel, high-current AC, and exhaust. Carbon monoxide from a running generator is lethal. Do not troubleshoot a running unit in an enclosed space.
Nothing below is a repair instruction for this system. What follows is what to observe and record — the work itself belongs to a technician.
Most likely causes
Ordered by how often each one turns out to be the answer, with the tell that distinguishes it.
Generator’s own breaker tripped
most commonEngine runs perfectly; the breaker on the generator housing is off.
Automatic transfer switch failure
commonShore power works normally; generator never transfers.
Generator not reaching governed speed
commonEngine note sounds low or uneven; output voltage or frequency is out of range.
Coach main breaker off
commonNeither shore nor generator power reaches the coach.
Brush or alternator-end failure
less commonEngine is perfect, output is zero, and the breaker is set.
What you can safely check
- 01
Find and check the generator’s own breaker
It is usually on the generator itself, not in the coach panel. This is the most commonly missed cause of this exact symptom.
- 02
Confirm shore power still works normally
If shore power delivers and generator power does not, the transfer switch or generator output is implicated and the coach wiring is proven fine.
- 03
Listen to the engine note under attempted load
An engine that sounds low, uneven or hunting may not be reaching governed speed, which affects output voltage and frequency.
- 04
Note whether anything at all comes on
Partial power — some circuits live and others dead — points somewhere different from complete absence.
What needs a technician
Transfer-switch diagnosis and replacement, output voltage and frequency testing, and any work at the alternator end. Transfer switches carry the full shore or generator load and are a live 120V assembly.
Parts typically involved
So you know what a quote should be naming. We publish no prices — real costs vary by market, season and technician, and a number we invented would look authoritative and help nobody.
- Automatic transfer switch
- Generator circuit breaker
- Brushes
- Voltage regulator
- Control board
When to stop troubleshooting
- There is any burning smell from the transfer switch or distribution panel — that assembly carries the full load and is a known failure point
- A CO alarm sounds while the generator runs
Can you still travel?
Driving is unaffected. Be aware that a failing transfer switch can also affect shore power later, so it is worth resolving before a trip that depends on either source.
Common questions
- Where is the generator breaker?
- On the generator itself in most installations — on the housing, often behind an access panel in the compartment — rather than in the coach’s interior distribution panel. Owners look in the coach panel, find everything set, and conclude the generator has failed. It is worth locating yours once while nothing is wrong.
- What does a transfer switch actually do?
- It decides whether the coach is fed by shore power or by the generator, and switches between them automatically. Because everything passes through it, a failing transfer switch can produce "generator runs but no power", "shore power does not arrive", or intermittent faults that look like several different problems. It is a common failure point precisely because it carries the entire load.
Related failures
For the whole system rather than this one symptom, see RV generator repair.
Next step
Work through structured triage for this system and you will end up with a written service brief: what you observed, in what order, and what has not been established yet. It is the document that lets a technician quote properly instead of guessing on arrival.
Being straight about what this is. No technician is signed to any territory yet — not one. We do not match you, dispatch anyone, or promise a call. What you get is the brief, and a request form that copies it to us so we know the demand is real. If you need someone today, take the brief and send it to a local technician directly; it works just as well that way.