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RV Tech Savvy: What’s Wrong With the Wiring on the Motorhome?

Originally Published in MotorHome Magazine

We have a 2016 Thor Windsport 31S. This motorhome has had one problem after another since I bought it used. First, the batteries would not charge. I found the leads reversed on the inverter and charger. It worked for about 800 miles, then burned up one of the batteries. I had the batteries replaced, and again they would not charge. I found that, 400 miles later, the positive battery cable was on the negative terminal. Now the generator won’t turn over, and the leveling system is inoperable. I have good DC power to the generator solenoid, but it is not picking up, and all other coach systems are functioning. I can’t find a good wiring diagram for this coach anywhere to trace the problems down. I’ve had lots of other of problems with this motorhome and wish I could afford to drive it off a cliff. Any ideas?
James Wegs | Lexington, Kentucky

It’s amazing you haven’t had an electrical fire. Oftentimes, circuit boards and other polarity-sensitive parts get fried when wires are connected backwards. If it hasn’t been too long since you bought it, I’d contact the seller. It’s fortunate that Thor is in business (800-860-5658) and is known for good customer service; you should be able to get body wiring information from the manufacturer. Your coach is built on a Ford F-53 chassis, and wiring diagrams are available from a number of sources, including eBay. Go online and use a search engine to find them. I suggest carefully tracing the main basic circuits to make sure the wiring and polarity are run correctly. Take out the fuses and install them to restart components one at a time, testing each before going to the next. If you don’t have the knowledge to do this, hire a certified RV technician. Good luck.

Genset Quits
I have a Generac NP 66 G propane generator. When I start the generator, it runs for about 2 minutes, then shuts down. It sounds like the kill switch has been pushed. I checked the fuel valve electromagnet; it has power when the generator is running, but no power when the generator shuts down. The generator will restart right away. After taking the magnet off the fuel valve and blowing it out, the generator would run for about 10 minutes. Then the magnet loses power and shuts down. What is required to get power to the fuel valve magnet? Can I run power to the magnet from another source and bypass the problem? I’ve read about the circuit board going bad and shutting things down as [the generator] warms up. I’ve checked the oil level and slightly overfilled it. The fuel tank is full. I’ve tried the oil level at slightly low, exactly on the mark and slightly high. I live in Colorado at 6,500 feet. The air temperature is 75 degrees Fahrenheit, and when it shuts down I can hold my hand on the engine, so it’s not overheating. What other safety devices besides oil and temperature are there? What are the problems with powering the fuel shutoff from another source?
Jeff Whilden | via email

I don’t recommend removing the safety devices and running the genset without them. An online manual is available. You might have a circuit board problem, but first try testing the sensors. Page 8 shows the sensors you are dealing with. There is a low-oil-pressure switch and a high-oil-temperature switch. The pressure switch is normally open when sufficient pressure is applied. So, you could disconnect the wire and try running the genset. If it doesn’t stall, the sensor is bad (assuming there is sufficient oil pressure). The oil-temp switch is normally closed, so if you connect the two wires together and the genset runs OK, that switch is bad. Both must work to get power to the electromagnetic valve. There are additional troubleshooting tips on page 16 of the same manual.

Fiberglass Roof Woes
We have a 2008 Forest River Georgetown 373DS that I bought new in 2009. I have noticed lately that the roof appears to be coming loose from the plywood or whatever material is under the fiberglass. It seems that the fiberglass has raised up in different areas. There aren’t any leaks. I have cleaned the roof every year and installed protectant from Camping World. What are your recommendations for fixing this issue?
Larry Beylor | White Post, Virginia

It is likely that moisture is collecting under the fiberglass and is swelling the wood underlayment, causing this problem. Push down on the bumps and feel if they are soft. I suggest carefully inspecting all possible leak areas on the roof and resealing them. This includes vents, air conditioners, etc. You will need to keep a closer watch on roof condition and anticipate major repairs eventually.

More RV Tech Savvy Discussion

Ken Freund has been a contributor to MotorHome magazine since 1988, and has written Coach & Powertrain and its predecessor, Powertrain Q & A, for two decades. He has been an RV, camping and travel enthusiast since he was a child.

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