Troubleshoot

Inverter / shore-power faults

Inverter alarms, no 120V pass-through, or an EMS that keeps rejecting the pedestal are transfer, overload, inlet, and programming problems more often than a “dead inverter.” Capture the exact fault, reduce load, and prove the shore path before you replace hardware. Prefer Text when the resets stop helping.

Symptoms

Inverter beeping — overload, low-battery cutout, high-temp, or fault code on display/app
Shore cord connected but no 120V pass-through to outlets / microwave / AC
GFCI or EMS rejecting pedestal: “open ground,” “reverse polarity,” high/low voltage
Transfer switch chatter, delayed transfer, or loads flicker during switchover
Microwave, air conditioner, or induction cooktop trips the inverter; other loads OK
Victron / Magnum / Progressive / Xantrex fault codes on panel or phone app
Works on generator, fails on shore (or the reverse)
Breaker trips instantly when shore is applied — even with loads off

Quick checks (owner-safe)

Confirm pedestal quality when safe: another pedestal, or a known-good surge protector path. Note EMS lights before resetting anything.
Photo the exact fault text/code on the inverter display or in VictronConnect / OEM app. Codes vanish after a blind reset.
Shed loads (AC, microwave, space heaters). Allow cool-down. Reset once per OEM procedure — do not spam resets into a thermal event.
Inspect shore cord ends, dogbone adapters, and inlet face for heat discoloration, bent pins, or corrosion.
Verify house battery voltage is high enough for inverter start (ties to 12V no-charge). Low bank → low-battery cutout that looks like an inverter failure.
Identify your transfer path: inverter-charger passthrough (MultiPlus/Quattro class) vs a separate transfer switch + inverter. The map changes the diagnosis.
Confirm input current limit / shore breaker size matches the pedestal (30A vs 50A) — an aggressive limit plus big loads equals nuisance overload.

When to stop DIY

Burning smell at inlet, dogbone, transfer switch, or inverter bay
Breaker will not reset, or trips instantly under no load
Aluminum/oxidized inlet blades or scorched plug face
Water intrusion in the inverter bay or around the shore inlet
Any work inside the inverter case (shock hazard / warranty)
Transfer switch or inlet replacement involving shore AC you’re not equipped to lock out safely
Repeated overload trips after loads are verified reasonable — wiring fault until proven otherwise

What UMRT diagnoses

We meter the shore path and the inverter behavior — DVOM on inlet, transfer, and DC supply; thermal where inlet pins, dogbones, or bus connections run hot under load. Goal: true overload vs wiring fault vs failed transfer vs programming — not a parts lottery.

True overload vs wiring fault vs failed transfer
Shore inlet / EMS / neutral-ground bonding issues
Inverter-charger programming (AES/AEF, UPS vs weak-AC ignore, input current limit)
Victron VE.Bus / MultiPlus fault interpretation — Victron Professional Certified Installer
Load calculation for microwave / AC / induction vs inverter continuous and surge ratings
Generator vs shore asymmetry (different quality, bonding, and frequency behavior)

Trip fee quoted before we roll. Diagnostic $150 applied if you proceed. Labor ~$150/hr. Corridor: MT · WY · ID · WA.

Map the symptom — shore only, inverter only, or both

Separate the failure mode before touching settings.

Shore only fails: pedestal, cord, EMS, inlet, transfer, or pass-through path. Inverter may invert from battery just fine.
Inverter only fails: DC supply, low battery, overload on invert, high temp, internal fault. Shore pass-through may still work on inverter-chargers.
Both fail: often shared transfer hardware, main AC distribution, or a cascade (dead bank + no shore acceptance).
Generator OK / shore bad (or reverse): quality, polarity, frequency, or EMS sensitivity — not automatically “bad inverter.”

Write the mode on paper. It cuts diagnostic time in half.

Shore path faults

Pedestal, cord, EMS

Pedestal breakers trip or run weak under RV load — try another site when practical before condemning the coach.
Cord and dogbone heat after 10–15 minutes under load = resistance. Replace damaged ends; don’t tape over a scorched face.
EMS / portable surge protectors that latch on open ground or reverse polarity are doing their job. Forcing past them without fixing the pedestal/inlet condition risks shock and equipment damage.
Voltage under ~108V AC (or chronic high voltage) damages appliances quietly — EMS that drops out on that condition is protecting you.

Open ground / reverse polarity honesty

Campground wiring faults are real. Your EMS saying “open ground” is often the pedestal — verify with a known-good tester/EMS on that pedestal when safe.
Coach-side open ground (broken ground conductor, bootleg neutral-ground bond in the wrong place, damaged inlet) is a different and serious problem — not a “clear the error” exercise.
Neutral-ground bonding belongs in one correct place for the operating mode (shore vs invert vs generator). Random bonding “fixes” create GFCI nightmares and shock risk. Leave bond topology to a qualified tech.

Inverter alarms and cutouts

Overload vs low battery vs high temp

Overload: load exceeds continuous or surge rating, or a shorted appliance. Shed, cool, identify the offender (A/C start surge and microwaves are frequent).
Low battery: bank voltage collapsed under invert load — charge path or capacity problem first (12V no-charge), not a new inverter.
High temp: blocked vents, failed fan, compartment heat soak, or repeated overload. Give cool-down time; fix airflow before the next reset.
Fault / internal: capture code. One clear code plus conditions beats three blind power cycles.

Load math that owners skip

Continuous rating ≠ surge rating. A 2000W inverter may not start a residential A/C compressor even if the nameplate “fits” on paper.
Induction cooktops and microwaves are harsh loads. If only those trip the unit, you may need load management — not a larger guess.
Parallel MultiPlus systems and Quattro installs have configuration and VE.Bus roles that DIY resets can upset — note settings before changing anything.

Pass-through and transfer behavior

Inverter-chargers can pass shore AC through while charging the bank. No pass-through with shore present points at acceptance (EMS, input relay, programming, failed transfer) more than “invert mode.”
Separate transfer switches: listen for transfer; delayed or chattering transfer under load suggests weak coil supply, bad switch, or flaky shore.
Input current limit set below the pedestal (e.g. 10A limit on a 30A site while A/C runs) looks like random overload — check the setting before replacing hardware.
Weak-AC / UPS modes: some units disconnect from marginal shore and invert instead. That can be correct behavior — or a sensitivity setting that needs adjustment for a known-soft pedestal.

Fault codes — capture first, replace last

Photo the display, app fault, and LED pattern.
Note: shore or invert, loads on, battery voltage, ambient/compartment heat, and whether a reset cleared it temporarily.
Victron VE.Bus / MultiPlus codes and Magnum/Xantrex equivalents mean specific things — swap-first wastes money.
Firmware and dip-switch / DIP / app profiles matter. Changing “a setting someone on a forum suggested” without a baseline is how pass-through disappears.

Deep dive when needed: Victron fault code guide · Electrical troubleshooting.

Generator vs shore asymmetry

Generator frequency/voltage drift can cause inverter-chargers to reject input while a simple transfer switch might still slam through — know which architecture you have.
Bonding and neutral switching differ between shore and generator operation. GFCI trips only on one source often point at bond/neutral issues.
Don’t “fix” generator rejection by defeating safety monitoring.

Inlet, dogbone, and 30A/50A realities

30A (TT-30) vs 50A (14-50) pedestals need the correct cord or a quality dogbone — cheap adapters fail hot under A/C load.
Wiggle test is not a repair. Heat at the inlet after a short run means resistance: replace inlet or cord ends, don’t keep camping on it.
Reverse dogbones and “cheater” configurations that defeat ground or neutral monitoring are unsafe — we won’t endorse them.
See also: 30A vs 50A guide.

Programming traps that look like hardware failure

Input current limit left at a storage/generator value (e.g. 5–10A) after a trip.
Weak-AC / UPS ignore settings fighting a soft pedestal — unit drops to invert and then low-battery alarms.
PowerAssist / AES features changing behavior under load; know what’s enabled before chasing “random” overload.
Split-phase / 50A Quattro or dual-Multi configs: one line accepted, one rejected — capture which leg and VE.Bus role before parts talk.
After a battery swap: charge voltage and low-battery cutout thresholds still set for the old chemistry.

Thermal and bay conditions

Inverter bays without airflow cook fans and trip high-temp under summer invert loads.
Dust, mouse nesting, and blocked intake screens are owner-visible — clear them cold, power off.
Thermal imaging on a diagnostic visit finds hot neutrals, failing transfer contacts, and undersized lugs before they arc.

Book a diagnostic

If you have burning smells, instant breaker trips, water in the bay, or faults that return after one clean reset and load shed, stop cycling the unit. Prefer Text — we quote the trip before we roll.

Prefer Text (616) 606-5277 · Book a Service · trip fee quoted before roll · diagnostic $150 applied if proceed

Don’t keep resetting into a thermal event. Pricing: trip $75/30 mi then $1.50/mi · labor ~$150/hr · diagnostic $150 applied. Credentials (text): Victron Professional Certified Installer · weBoost Authorized Installer · Peplink Certified Associate · Dometic Professional Certified · Starlink install capability. Corridor: MT · WY · ID · WA.

Related guides

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Prefer Text — (616) 606-5277. Trip fee quoted upfront before we roll.

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