Electrical and Power
RV and Fleet Electrical System Repair Serving Long Beach
About 10 min left
OCRV Center diagnoses and repairs 12 volt and 120 volt electrical systems on recreational vehicles, vans, commercial trucks and fleet units, including converters, transfer switches, wiring, panels and shore power. Electrical work runs $285 for a diagnostic to $5,000 for a system wide rewire or panel replacement.
An RV has two entirely separate electrical systems sharing one vehicle, and most owner confusion starts right there. The 12 volt system runs lights, pumps, fans and the furnace off the house batteries. The 120 volt system runs air conditioning, the microwave and the outlets off shore power or a generator. They interact through the converter and the transfer switch, and a fault in one presents as a symptom in the other constantly.
That is why guessing at RV electrical problems is so expensive. The lights dimming when the water pump runs is a battery and cable problem. The outlets dying while the lights work is a transfer switch or breaker problem. They feel similar and they are not related at all.
Twelve Volt House Systems
The 12 volt system is where most RV electrical complaints originate, and voltage drop is the underlying cause of a large share of them. Long runs of undersized wire, corroded ground connections and loose terminals all produce voltage at the device that is well below what the battery is reading.
The symptom is equipment that works intermittently or works weakly. Slide motors that seem tired, pumps that cycle oddly, lights that dim under load. We measure voltage at the device under load rather than at the battery, because that is the only number that tells you anything.
Grounds Are the Usual Culprit
On a vehicle, ground is chassis, and chassis grounds corrode. A ground connection with resistance behaves exactly like an undersized positive wire, and it is far harder to find because nobody looks there first.
We test grounds by measuring voltage drop across the ground path under load. A good ground shows nearly zero. Anything above a couple tenths of a volt is a problem.
One Hundred Twenty Volt Systems and Shore Power
Shore power comes in through the inlet, passes through the transfer switch, and distributes through the breaker panel. Each of those is a common failure point, and the transfer switch most of all because it carries full load through mechanical contacts that arc every time it operates.
Burnt transfer switch contacts are one of the most frequent findings on coaches over ten years old. The symptom is losing 120 volt power on one leg, which kills half the outlets and one air conditioner while everything else appears fine.
Converters, Chargers and the Charging Path
The converter turns shore power into 12 volt to run the house system and charge the batteries. A failing converter produces batteries that never fully charge, and owners almost always blame the batteries first and buy new ones.
We test converter output voltage under load and check whether it is reaching the correct absorption and float stages. Replacing batteries when the converter is the fault is a common and completely avoidable expense.
Wiring, Panels and Rodent Damage
Rodent damage to wiring is far more common in stored vehicles than owners expect, particularly on units that sit for a season. The damage is usually in wiring runs behind panels and under the coach where it stays hidden until something stops working.
We trace and repair damaged harness sections properly, replacing the affected run rather than splicing repeatedly. On extensive damage a section rewire is both cheaper and more reliable than chasing individual faults through a chewed harness.
What Is Included
- Voltage measured at the device under load, not just at the battery
- Ground path voltage drop tested rather than assumed
- Transfer switch contacts inspected on any 120 volt complaint
- Converter output verified through its charging stages before batteries are condemned
- Wiring runs traced and damaged sections replaced rather than repeatedly spliced
- Correct wire gauge and overcurrent protection on all new circuits
- Full system function test on both 12 volt and 120 volt before release
Our Process
- 1
Symptom Capture
What fails, under what conditions and on which system recorded, since 12 volt and 120 volt faults present similarly.
- 2
Source Testing
Battery condition, converter output and shore power quality measured at the source.
- 3
Load Testing
Voltage measured at the affected device while it operates, which is the only reading that identifies drop.
- 4
Ground Verification
Voltage drop across the ground path measured under load to find corroded chassis connections.
- 5
Circuit Tracing
Affected run traced through panels and cavities to locate damage, corrosion or undersized wire.
- 6
Repair
Components replaced, harness sections renewed, connections cleaned and protected to correct gauge and protection.
- 7
System Test
All affected circuits and both systems exercised under load before the vehicle is released.
Frequently Asked Questions
Can you fix the electrical system on my cargo van?
Yes. Cargo van electrical work covers the chassis system, any auxiliary house system added during upfit, shelving and equipment power, lighting circuits and inverter installations. The most common faults we find on working vans are chafed harness sections where wiring passes through a bulkhead without a grommet, and corroded grounds at equipment mounting points. Both produce intermittent symptoms that get misdiagnosed as component failures.
My RV lights dim when the water pump runs. What causes that?
Voltage drop, almost certainly, and usually from a corroded ground or undersized cable rather than a bad battery. When the pump draws current, the resistance in the circuit produces a voltage loss that everything else on the system experiences as dimming. We measure voltage at the device under load rather than at the battery, because a battery reading 12.7 volts while the device sees 11.4 tells you exactly where the problem is.
Half my outlets stopped working but the lights are fine. Why?
Because those are two different systems. Lights run on 12 volt from the house batteries, while outlets run on 120 volt from shore power or the generator. Losing 120 volt on one leg kills half the outlets and typically one air conditioner while everything on 12 volt continues normally. The usual cause on coaches over ten years old is burnt transfer switch contacts, since that switch carries full load through mechanical contacts that arc on every operation.
How do you repair electrical systems damaged by rodents?
By replacing the affected harness sections rather than splicing individual wires repeatedly. Rodent damage is rarely a single wire, and a harness with a dozen splices becomes a permanent source of intermittent faults. We trace the damage, determine its extent, and renew the run. On extensive damage a section rewire is both cheaper and far more reliable than chasing faults through a chewed harness for the next several years.
Electrical System Repair is performed in shop at OCRV Center, 23281 La Palma Ave, Yorba Linda, CA 92887, serving Long Beach, California and the surrounding region. Call (949) 799-3387 to discuss your vehicle.
Get Your Vehicle Looked At Properly
Call the shop, describe what happened, and we will tell you what the realistic scope and timeline look like. All work is performed in shop at our 35,000 square foot facility.