# RV Electrical Repair for San Clemente Owners

> OCRV Center diagnoses and repairs RV electrical systems on both sides of the coach: 12V house wiring, batteries and converters, and 120V shore power, transfer switches and inverters. Work is performed in our 35,000 square foot Yorba Linda shop, about 45 minutes from San Clemente.

**Type:** Repair service  
**Canonical:** https://ocrv.pro/repairs/electrical-systems  
**Updated:** 2026-07-29

## Summary

We trace 12V and 120V faults to the actual cause: converters, inverters, transfer switches, corroded grounds and parasitic draw. Diagnostic time runs $285 per hour, credited back.

Electrical faults in an RV are the hardest problems to buy your way out of, because the symptom almost never sits where the fault does. A refrigerator that quits on shore power but runs on the generator is not a refrigerator problem. A house battery that dies in four days is usually not a battery problem. The coach is two separate electrical systems sharing one chassis, and the failure is almost always at the boundary between them.

Most owners arrive here after buying parts. New batteries, then a new converter, then a new inverter, and the symptom is still there. That sequence is understandable and it is expensive, because every one of those parts was a guess. A clamp meter on the right conductor for ten minutes answers the question that three thousand dollars of parts did not. That is what the diagnostic hour buys you.

San Clemente adds a specific failure mode that inland owners do not fight as hard. Marine layer humidity and salt aerosol off the water at Shorecliffs and the Pier Bowl work into every crimp, every ring terminal and every ground stud on the underside of a coach. Corroded connections do not fail cleanly. They add resistance, generate heat, drop voltage and produce symptoms that look exactly like a dying component.

## Your Coach Runs Two Electrical Systems and They Fail Differently

An RV carries a 12V direct current system and a 120V alternating current system, and they are joined at three or four places. The 12V side runs lights, water pump, furnace blower, slide motors, leveling, control boards and the fridge control logic. The 120V side runs the air conditioners, the microwave, the outlets, the water heater element and sometimes a residential refrigerator. When 120V is present, a converter charges the 12V bank. When it is absent, an inverter may push the other direction.

That interconnection is why symptoms cross over. A failed converter looks like a battery problem, because the bank slowly discharges while plugged in. A failed transfer switch looks like a generator problem, because the coach never sees generator output. A tripped inverter looks like a refrigerator problem, because the residential unit is the only load on that circuit. Owners chase the appliance. We chase the source.

Our first move on any electrical complaint is to establish which system is actually at fault and where the voltage stops. That means measuring at the pedestal, at the inlet, at the transfer switch, at the main breaker, at the converter output, at the battery terminals and at the load. Seven measurements, in order, no guessing.

- **12V house side:** Battery bank, disconnect solenoid, fuse and distribution panel, chassis grounds, and every low current circuit including lighting, pumps, blowers, slide controllers and control boards.
- **120V shore side:** Shore cord and inlet, surge protection, automatic transfer switch, main breaker panel, GFCI circuits, and the hard wired loads such as roof air, water heater element and microwave.
- **The converter:** Takes 120V in and produces 12V charging output. Progressive Dynamics and WFCO units are the common originals. A dead converter presents as a battery that never holds while plugged in.
- **The inverter:** Takes 12V from the bank and produces 120V for selected circuits. Magnum, Xantrex and Victron are the units we see most. Failure usually shows as one dead sub panel, not the whole coach.
- **The chassis side:** On motorized coaches there is a third system: engine start battery, alternator and a battery isolator or DC to DC charger tying it to the house bank. That tie point fails often and is easy to miss.

## Tracing Shore Power From the Pedestal to the Panel

A 50 amp coach is not running 50 amps. It is running two independent 50 amp legs at 120V each, sharing a neutral, which is why half the coach can go dark while the other half runs fine. That single fact explains most of the shore power calls we take. One leg dropped. The air conditioners on that leg quit, the outlets on that leg quit, and everything on the other leg keeps working, so it does not look like a power problem at all.

The chain has specific weak points. Shore cord ends overheat and carbonize at the blades, especially on 30 amp coaches drawing near capacity in summer. The inlet receptacle behind the door burns at the terminal screws. The automatic transfer switch contacts pit, arc and eventually weld or open. Neutral connections loosen from road vibration and produce voltage that swings wildly under load. We measure at each junction rather than replacing the whole chain.

Campground pedestals in Southern California are frequently the actual fault. Low voltage under 105V or an open ground at the pedestal will damage compressors and control boards, and the coach gets blamed. A hardwired surge and voltage protector with a display is the cheapest insurance in this category and we install them regularly.

- **Automatic transfer switch:** Switches the coach between shore and generator. Contacts pit from arcing under load. Symptom is generator running with no output to the coach, or one leg missing after a switchover.
- **Shore cord and inlet burn:** Heat damage at the blades or terminal screws adds resistance, which adds more heat. Discoloration at the plug is a repair now item, not a watch it item.
- **Open or floating neutral:** Produces one leg reading high and the other low, damaging electronics on the high leg. It is the fastest way to lose several control boards in a single evening.
- **Reverse polarity and open ground:** Common at older pedestals. GFCI outlets will not reset and the coach may show voltage on metal surfaces. We test at the inlet before condemning anything inside.

## AGM or Lithium: Matching the House Bank to How You Actually Camp

The lithium conversion question comes up on almost every intake, and the honest answer is that it depends on whether you dry camp. If you spend your nights at Doheny or San Onofre on shore power, a quality AGM bank does the job for a fraction of the cost and there is no reason to spend more. If you boondock, LiFePO4 changes what the coach can do, because you can use roughly 90 percent of rated capacity instead of 50 percent and it recharges far faster.

A lithium conversion is not a drop in swap, whatever the box says. LiFePO4 chemistry needs a charge profile that most stock converters do not produce, so the converter usually gets replaced or reprogrammed. The alternator charging path needs a DC to DC charger, because feeding a lithium bank directly through an isolator can cook an alternator. Low temperature charge protection matters less here than in Colorado, but it still belongs in the build.

Battery compartment ventilation, cable gauge and fusing all change too. A lithium bank will happily deliver enough current to melt undersized cable that was fine on flooded lead acid. We resize the conductors, add a class T fuse at the bank and verify the disconnect is rated for the new current before the bank goes in.

- **AGM house bank:** Sealed, tolerant of the stock converter profile, no build changes required. Usable capacity is about half of rated. Best value for owners who are on shore power most nights.
- **LiFePO4 conversion:** Roughly 90 percent usable capacity, far faster recharge acceptance and a fraction of the weight. Requires a matched charge profile, correct fusing and usually a converter change.
- **DC to DC charging:** Isolates the alternator from the house bank so a hungry lithium bank cannot overload it. Victron and similar units are what we fit on motorized coaches during a conversion.
- **Cable and fusing audit:** We size conductors to the new current, install a class T or equivalent fuse at the positive post and confirm the battery disconnect and shunt are rated for the bank.
- **Battery monitoring:** A shunt based monitor at the negative post reports actual amp hours in and out. Without one, state of charge on lithium is a guess, because resting voltage barely moves.

## Parasitic Draw: Why the Bank Is Dead After Four Days in Storage

A coach sitting on a storage lot with the disconnect off should lose almost nothing. When owners come back to a dead bank after a week, there is a load still connected downstream of the disconnect, and there almost always is. Propane and carbon monoxide detectors, radio memory, the refrigerator control board, the leveling controller, the antenna booster and any aftermarket tracker all sit on the always hot side in most builds.

The measurement is straightforward. We disconnect the negative cable, put a clamp or an inline meter in series, record the baseline draw, then pull fuses one at a time until the number drops. What takes time is that the fault is often intermittent, or it is a slide controller that only wakes up every few hours. Sitting with a data logger overnight finds those. Guessing does not.

The other half of this category is the disconnect itself. Battery disconnect solenoids stick closed, and the owner has no way to know, because the panel lights go out either way. We verify actual current flow with the switch in both positions rather than trusting the indicator.

- **Baseline draw measurement:** A healthy coach with the disconnect open should read well under 100 milliamps. Anything above roughly half an amp will flatten a typical bank inside two weeks of storage.
- **Circuit by circuit isolation:** Fuses pulled in sequence with the meter inline, results recorded on the panel map so the same circuit does not get retested on the next visit.
- **Stuck disconnect solenoid:** The most common single cause. The switch reports open, the contacts stay closed, and the whole coach continues to draw while it sits. Verified by measurement, not by the indicator lamp.
- **Aftermarket additions:** Trackers, alarms, dash cameras, cellular boosters and inverter remote panels installed on always hot circuits. Each is small. Four of them together will empty a bank in a long weekend.

## Salt Air, Rodents and the Two Ways RV Wiring Actually Dies

Coastal storage in San Clemente is hard on wiring in a way that owners rarely account for. Salt aerosol settles on the underside of the coach, condenses in the marine layer overnight and works into crimp barrels, ring terminals, ground studs and the back side of every exterior light. Copper turns green, resistance climbs and the circuit starts behaving oddly under load while testing fine with a meter at rest. Voltage drop testing under load is the only way to catch it.

The second killer is rodents. Coaches stored under trees or on dirt lots in Rancho San Clemente and inland Orange County get chewed harnesses, and modern low voltage wire insulation is attractive to them. We see chassis harnesses, slide harnesses and 12V trunk lines opened up, and we see nests packed against DC junctions where they eventually short. Repair is section replacement with proper crimps and heat shrink, not tape.

Both problems get repaired the same way: cut back to clean copper, replace the damaged run with correctly sized marine grade conductor, use adhesive lined heat shrink at every termination and support the harness so it is not sitting in a wet channel again. Wire nuts and electrical tape do not survive a year of coastal storage.

- **Voltage drop testing:** Measuring across a connection while the circuit carries load. A corroded joint that reads zero ohms at rest can drop two volts under a pump or blower load.
- **Ground stud service:** Chassis ground points corrode first because they are unpainted metal at the frame. Cleaning, re-terminating and sealing the grounds resolves a surprising share of ghost faults.
- **Harness section replacement:** Rodent damaged runs are cut back to sound insulation and replaced with correctly gauged conductor, adhesive lined heat shrink and proper strain relief.
- **Exterior fixture rework:** Marker lights, awning lights and camera feeds are the most exposed terminations on the coach. We reseal them during any exterior electrical repair as a matter of course.

## Inverters, Chargers and Power Upgrades Worth Paying For

An inverter converts house battery power into 120V for selected circuits. Two categories exist and the difference matters. Modified sine wave units are cheap and will run resistive loads, but they buzz through audio, run some motors hot and confuse certain control boards. Pure sine wave is what belongs in a coach with a residential refrigerator, a CPAP, a microwave inverter mode or any modern electronics. We fit Magnum, Xantrex and Victron units depending on the coach and the load profile.

Sizing is where most aftermarket installs go wrong. A 3000 watt inverter drawing near capacity pulls roughly 250 to 300 amps from the 12V side, which requires very heavy cable over a short run and a bank that can actually deliver it. An inverter matched to cable and bank works for years. An oversized inverter on stock cable trips on low voltage, gets returned as defective and gets replaced with an identical unit that does the same thing.

The upgrades we recommend most often are unglamorous: a hardwired surge and voltage protector, a shunt based battery monitor, LED conversion of remaining incandescent fixtures, and a proper inverter remote panel so you can see what the system is doing. All four reduce the number of times you need to call anyone.

- **Pure sine wave inverters:** Clean output for electronics, motors and medical equipment. The correct choice for any coach with a residential refrigerator or an inverter driven microwave.
- **Inverter charger combination units:** One unit that inverts on battery and charges on shore, replacing the separate converter. Simplifies the system and typically improves charge quality on lithium banks.
- **Hardwired surge protection:** Protects against low voltage, open ground, reverse polarity and surges at the pedestal. Installed at the inlet so it cannot be forgotten or stolen.
- **LED lighting conversion:** Cuts interior 12V draw substantially, which matters most for dry camping. Also removes the heat that ages incandescent fixture housings and lenses.
- **Camera, antenna and connectivity wiring:** Backup and side camera systems, roof antenna and satellite equipment, and Starlink hardware all need proper routing, sealed roof penetrations and a fused supply.

## Pricing

| Line item | Range | Hours |
| --- | --- | --- |
| 12V and 110V diagnostics and repair | $285 to $5,000+ | 1 to 20 |
| House battery replacement, AGM, lithium or LiFePO4 | $500 to $5,500 | 2 to 10 |
| Inverter and charger replacement | $750 to $4,500 | 3 to 14 |
| Transfer switch and shore power diagnostics | $285 to $1,500 | 1 to 6 |
| 12V and shore power electrical wiring | $400 to $5,500 | 2 to 22 |
| Lighting and wiring diagnostics | $285 to $2,500 |  |
| LED lighting upgrades | $250 to $2,500 |  |

## Process

1. **Intake and symptom history** (Day 1). We ask what fails, when it fails and what was already replaced. Prior parts swaps tell us where not to look, which saves diagnostic hours.
2. **Diagnostic hour** (Day 1 to 2). Measurements taken in sequence from shore inlet to load, with the coach on shore power, on generator and on battery. Billed at $285 per hour with a one hour minimum, credited against an authorized repair.
3. **Written findings and authorization** (Day 2 to 4). You get measured values and a line item plan. If the fault is intermittent, we tell you that plainly and propose a data logging period rather than guessing.
4. **Repair or component replacement** (Day 3 to 14). Harness sections, converters, inverters, transfer switches, panels or battery banks fitted with correct gauge, fusing and terminations.
5. **Load verification** (Final 1 to 2 days). Every affected circuit is run under real load. Voltage drop is measured at the far end, not at the panel, and the coach is cycled through shore, generator and battery.
6. **Handover and documentation** (Pickup day). We walk you through what was found, what was changed and what to watch. Panel maps and measured baselines go home with the coach.

## What is included

- Systems estimate at $150, credited back against an authorized repair
- Voltage measurement from the pedestal through the inlet, transfer switch, panel and load
- Battery bank load testing and state of charge verification under real load
- Converter and inverter output testing with charge profile verification
- Automatic transfer switch contact inspection and switchover testing
- Parasitic draw measurement with circuit by circuit fuse isolation
- Ground stud cleaning, re-termination and sealing at chassis points
- Harness section replacement with marine grade conductor and adhesive lined heat shrink
- Correct cable sizing and fusing on any battery or inverter change
- Written findings with measured values, not a parts list

## Questions

### Why does my RV battery die in a few days even with the disconnect switch off?

Because something is still connected downstream of that switch, or the disconnect solenoid is sticking closed. Detectors, control boards, radio memory, leveling controllers and aftermarket trackers commonly sit on the always hot side. We measure baseline draw with a meter in series, then pull fuses in sequence until the number drops. Intermittent draws get a data logger overnight rather than a guess.

### What does RV electrical diagnosis and repair cost?

Diagnostic, scan and programming time is $285 per hour with a one hour minimum, and that hour is credited against an authorized repair. Mechanical and electrical labor is $260 per hour. Complete diagnosis and repair ranges from $285 for a single circuit up to $5,000 and beyond on a full harness or panel rebuild running 20 hours or more.

### Is a lithium house battery conversion worth it for my coach?

If you spend most nights on shore power, no. A quality AGM bank does the same job for far less. If you dry camp, yes, because LiFePO4 gives you roughly 90 percent usable capacity instead of 50 percent and recharges much faster. The conversion typically also requires a matched charge profile, a DC to DC charger on motorized coaches, and resized cable and fusing.

### Half my outlets and one air conditioner stopped working. What is that?

On a 50 amp coach that is almost always one lost leg. A 50 amp service is two 120V legs, so losing one takes out everything on that side while the rest of the coach runs normally. The usual causes are a burned shore cord end, a damaged inlet, a pitted transfer switch contact or a loose neutral. We measure at each junction rather than replacing the whole chain.

### Do you cover electrical damage on an insurance claim?

Yes, when the damage is claim related. Wiring destroyed in a collision, a lightning or surge event, rodent damage on comprehensive coverage, and water intrusion damage to panels and boards are all commonly payable. We document the affected circuits with photographs and measured values and submit that to your adjuster directly.

### How long does electrical work take, and can I wait for it?

Plan on leaving the vehicle. A single circuit fault can be found and fixed in a day, but a parasitic draw or an intermittent fault needs overnight logging, and a full battery and inverter build runs one to two weeks with parts. We give you a written completion date at authorization and update it if parts move.

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