1. Home
  2. Tech
  3. Tech Q&A: Motorhome Magazine
  4. RV Tech Savvy: Wonky Windshield Wipers

RV Tech Savvy: Wonky Windshield Wipers

Originally Published in MotorHome Magazine


Q icon

I have a 2015 Thor Challenger 37 GT with 22,000 miles on the odometer. On a trip to the Southwest, our windshield wipers went crazy. First, they were out of sync and then they completely stopped; the left wiper was stuck beyond the edge of the windshield and the right one in front of the grille. I discovered a recall from Thor that addressed that problem and had it repaired. When we picked up the coach, I tested the wipers and they worked great with the ignition switch on but not with the engine running. After starting the engine, the wipers ran at slow speed only, even with the switch on intermittent or high, and they kept running even when turned off. To stop the wipers, I have to stop the coach and turn off the engine. I have two trusted mechanics, but they can’t find the problem. We have replaced the wiper motor, wiper transmission and the wiper control stalk switch. Thor has no electrical schematics, only a troubleshooting guide that doesn’t cover my problem.
Any suggestions would be appreciated.

Steve Clark | Tatum, Texas

A iconBecause you have a Ford chassis, parts are supplied by Ford and the troubleshooting information would be in the applicable Ford shop manual. Based on your description, it’s quite possible that the wiper control module has a bad ground, is getting feedback from an adjacent circuit (perhaps due to faulty grounding) or has already failed. That’s ironic, because the wiper control module is the only component in the wiper system the mechanics haven’t replaced in their “shotgun” approach to fixing the problem. I have found that the control module is very susceptible to electrical surges and spikes, which tend to destroy these expensive components. Therefore, make sure you shut off the windshield wipers before shutting off the engine during routine operation.

Two Questions: Side-wall Blistering and Flaking

Q iconWe have a 2005 Alfa See Ya! Class A motorhome. The first trip in our motorhome was to Alaska, over 9,000 miles, and everything went well. However, the coach has a serious problem with exterior side-wall blistering and flaking, and nobody seems to have an answer. The flaking is primarily on the bottom half of the coach. Is there anything I can do to fix the problem?

Dick Wilbert | Pittsburg, Kansas

Q iconI am an avid reader of MotorHome and read it cover to cover. We own a 2004 Alfa See Ya! motorhome, which has side-wall blistering. I am also one of the hundreds who purchased an Alfa motorhome not knowing about the blister problem they had. We love our motorhome, all its features, etc., and it is mechanically very sound. The only problem is that its appearance due to the blistering problem is now getting out of hand. I was wondering if you could tell me how others have solved the problem, or suggest ways to solve the problem and possibly recommend a company that has had experience fixing the problem?

Frank Homa | Crofton, Maryland

A iconThe cause reportedly can be traced to the side-wall material supplier and a problem with the resin mix when the fiberglass was formed. The problem is exacerbated as coaches get older and moisture wicks in behind the walls from various sources, including leaks around windows, roofs, etc. Alfa had been fixing coaches with this problem under warranty until the company went out of business. I hate to be the bearer of bad news, but the solution for most of these coaches is to replace affected exterior side walls. This can run into the tens of thousands of dollars. One company that does this type of work is Master Tech RV in Elkhart, Indiana (866-895-4556).

Reduced Engine Power

Q iconWe own a 2004 Holiday Rambler Vacationer that had a dead battery. A new battery was installed, but since then, we have had a “reduced engine power” message on the dash. The engine starts, but there’s not enough rpm to drive it. We had a meter placed to check codes and nothing showed up. We have checked the fuel-filler cap and it’s on tight. We live in a small rural area, and nobody here seems to know what to do. Any advice would be appreciated.

Carla Reidle | via email

A iconHave a tech question?A loose gas cap should not cause this problem. Many GM engines come equipped with a Reduced Engine Power (REP) warning light, similar to the Check Engine Light (CEL). Vacationer motorhomes were built on Ford and GM chassis, which is why it’s important to provide this information when writing to us. When the REP light (or both REP and CEL light) comes on, you’ll notice the engine barely responding to the accelerator. This can be really disconcerting if the problem happens while you’re climbing a grade or are in heavy traffic. Among the more common issues that will cause this warning light to illuminate is the harness connecting to the throttle position sensor (TPS), or the TPS itself. Some other problems that can illuminate the REP light are the throttle body (including wiring), oxygen sensor, accelerator pedal position sensor (APP) or harness, low engine oil pressure, or low coolant and overheating.

Even if the CEL hasn’t come on, rescan the PCM with a commercial-duty tool. You may have a pending code that can guide you to the source of the problem. A malfunctioning sensor or actuator may cause the computer to receive faulty signals, causing changes in the fuel mixture and a reduction in engine power. Whatever codes you find, test the circuit or components indicated by the trouble code. Another possibility is that rodents have chewed on wiring, which should be inspected carefully.

Hot “C” Cab

Q iconWe have a 2019 Thor Freedom Elite 24-foot Class C motorhome with a Ford V-10 engine. When we are traveling, the floor of the cab and engine doghouse cover get excessively hot no matter what the outside temperature. Do you have any suggestions on how I can reduce the amount of heat in the cab area?

Lawrence Weis | Sacramento, California

A iconThis is a common complaint with Class C motorhomes in hot weather because the cab is built over the rear of the engine and is so close to heat generating components. I’ve written about this before, but it’s been a while, so let’s have a go.

Make sure the doghouse rubber sealing strip is in place and secured all the way around. Check for insulation under the doghouse cover. Check for a missing heat shield between the exhaust pipes and the floor. Additional floor insulation can be added by removing the seats and floor covering and installing an aftermarket stick-on heat shield mat from Thermo-Tec  or a similar product designed to withstand high temperatures. It can be purchased online from eBay or Amazon, or at some auto parts stores. If you don’t want to do it yourself, you can take it to a shop that does auto upholstery or car-stereo installations. These types of service facilities usually sell and install such products.

Vexing Vibration

Q iconI have a 2018 Winnebago View motorhome on a Mercedes-Benz Sprinter chassis. From the day I bought it, it’s had a vibration problem at 60 mph. The vibration continues until I slow down. It only seems to vibrate on smooth roads. Mercedes-Benz tried to spin balance the tires three times; that made it worse. I took it to a local shop and they made it better; however, the tires wore on the inside. Do you have any suggestions?

Gary Silvis | via email

A iconAssuming it’s the front tires wearing on the inside, not the rears, the problem is likely due to misalignment. Older vehicles with high mileage may also have worn steering components, which cause looseness and tire wear. This type of wear can cause the tires to go out of balance. Front tire imbalance can be felt more through the steering wheel, whereas rear tire imbalance can be felt more through the floor and seat. Have the wheel alignment checked due to the uneven tire wear. Try rotating the tires front to rear and see if the vibration moves aft with the change. There’s also a possibility that part of the vibration is caused by driveline imbalance. This should be checked if tire and alignment changes don’t solve the problem.

More RV Tech Savvy Discussion

Ken Freund portraitKen 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’s been a camping and travel enthusiast since he was a child.



Ken FreundMotorhome 101Motorhome DIYMotorHome TipsRV Tech Savvy

Subscribe to Wildsam Magazine today, Camping World and Good Sam’s magazine of the open road.

Just $19.97 for a year’s subscription.


Please login or register to view archived articles.

Sign In

Do not have an account? Create New Account