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Dinghy Towing Methods: Let’s Discuss

Originally Published in MotorHome Magazine



Where can I find the pros and cons of towing a car or SUV on the ground, on a dolly or on a trailer behind my motorhome?

Jay Garwood | Via email


It has been a while since I have covered this topic in my column, so it’s a good time to review. I’m just going to cover the major points, but there are also minor points that some folks might come up with. The main advantages of towing “on the ground” as you say, which is commonly called “flat towing” and is accomplished with a tow bar, is the simplicity, relatively lower cost and lightness of this method. Motor­Home’s annual dinghy towing guides list the vehicles that are approved by their manufacturers specifically for flat towing.

The tow bar can be stowed inside the vehicle or in a storage compartment, or left mounted on the back of the motorhome, depending on the tow-bar design. There is no need to store or park a trailer or tow dolly separately, and you don’t have to buy or maintain one, replace the dolly/trailer tires or pay for licensing fees, etc.

A tow dolly can allow a vehicle, such as many front-wheel-drive models (typically with automatic transmissions), which are not approved for flat towing, to be towed behind the motorhome safely without fear of damage to the drivetrain. Tow dollies are also available with brakes, which takes care of the need for an auxiliary braking system.
Trailers allow virtually any vehicle to be towed behind a motorhome, regardless of its drivetrain design or limitations regarding towing. For example, with a trailer, you can tow all-wheel-drive vehicles that must not be towed with their wheels turning (to prevent drivetrain damage). Trailers should be fitted with brakes sufficient to handle the weight of the vehicle carried and trailer weight.


Diesel Exhaust Fluid

Is there is a difference between the brands of DEF? There can be a big difference in price.

Pete Whitehouse | Clayton, Delaware


That’s a very good question, Pete. Because the answer is important to a lot of diesel owners, and the result of getting the wrong product can lead to very expensive problems, we’ll take an in-depth look.

Have a tech question?To begin with, let’s cover the legal definition of diesel exhaust fluid (DEF). It must meet the guidelines established by the International Organization for Standardization, ISO 22241, which maintains quality requirements for DEF production, storage and distribution. To qualify as DEF, it must contain a urea concentration of 32.5 percent by weight. This concentration has a freezing temperature of 12 degrees Fahrenheit, the lowest of various urea-water mixtures. There are strict, low limits on impurities to ensure reliable operation of the Selective Catalytic Reduction (SCR) system, which controls emissions.

The ISO DEF standards also require that the water in the formulation be purified by distillation or deionization. Deionized water is critical to the manufacturing of DEF. The slightest amount of contaminants in the water or urea will cause the fluid to not meet the ISO 22241 specification. Elements such as aluminum, calcium, copper, iron, zinc, magnesium, chromium, nickel, sodium and potassium can all damage SCR systems.
Any product that doesn’t meet ISO 22241 standards cannot legally be called DEF or sold as DEF. However, with growing demand, there will likely be unlicensed products that don’t meet ISO standards but are still urea solutions. Agricultural-grade urea may contain impurities such as aldehydes and excessive levels of biuret, which damage SCR systems. Some failures may be immediate, while others might take from days to years.

In addition to meeting the ISO 22241 specification, only products that are licensed by the American Petroleum Institute (API) may be called DEF. To protect yourself, use only known brands of DEF that use pharmaceutical-grade urea. However, feel free to shop for the best price among these brands and container sizes, keeping in mind that DEF has a limited life. Containers should be stored in a cool place to ensure longevity.
For a searchable directory of API-licensed DEF products, visit www.apidef.org/directory.aspx.


Jeep Cherokee Towing Update

I read MotorHome regularly and have been watching the articles on the Jeep Cherokee “death wobble” that RVers have experienced. I would like to add to the story.

I tow a 2014 Jeep Cherokee behind my 2002 Fleetwood Revolution. After experiencing the wobble I tried calling Chrysler, to no avail. I was advised by other RVers to check with my local Jeep dealer and have a special wiring harness installed as provided by Chrysler to fix this problem. Since I was traveling in Wisconsin, I went to a dealer I know and had the wiring harness installed, but I wish to report that this is not a complete fix.

To activate the harness, you need to install a 10-amp fuse, which is connected to the battery, and flip a toggle switch installed inside the center console in the car. I was told that this would keep the steering stabilizer on while the car was off and being towed.

I left Wisconsin on a trip to South Dakota. The battery went dead on the way. In my mind, once the battery was dead, then the steering stabilizer was no longer active either, since it had no power. Upon arrival in South Dakota, I struggled to gain entry to my car. I tried to re-engage the transfer case but was unable to. I had a small charger with me and after plugging into the battery, I was able to re-engage the transfer case … or so I thought. The lights said it was reset; however, when releasing the car from the motorhome, the car began to roll. After additional struggles, I was able to get the transfer case reset. The same thing happened on my return to Wisconsin. Then, the check engine light began appearing on my dashboard.

I took it back to the dealer and was advised that there were many codes for this and all of them were related to the wiring-harness fix. I was also told that since the battery keeps draining to a dead point, a couple more times of that will ruin the battery and at best I will need to replace it or it may not start at all. I have to say, I did not experience the wobble again, but it has now created a whole new set of problems.

I am worried about the safety of myself and other RVers who might think that this fixes the problem. I would like to see Chrysler get further involved to get this handled. Any RVers who have gotten the fix, please be aware that it can cause additional problems.

Harvey Piette | Clermont, Florida


Thanks for your useful firsthand report on this modification. I am truly disappointed that Jeep doesn’t step up and cover the cost of the auxiliary wiring harness, since it is necessary in order to safely allow dinghy towing, which the company claimed these vehicles were capable of and approved for. I agree that repeated deep discharges of the battery will ruin it; sometimes you only get one chance. You can fix the battery discharge problem by installing a charge line from the motorhome to the Jeep. Not only will this prevent the dead-battery problems, but it will also provide power for an auxiliary braking system, which you absolutely should have for safety reasons.


Ken FreundMotorhome How TosRV TechRV Tech Savvy

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