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RV Tech Savvy: Towing a Cadillac

Originally Published in MotorHome Magazine

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This is in regard to your 2018 Guide to Dinghy Towing. We recently purchased a 2017 Jayco Seneca motorhome and are wondering if you have any information on the use of a 2015 Cadillac SRX4 as a dinghy vehicle. This car is an AWD with automatic transmission and a button in the console to push in so that the transmission can be taken out of park to neutral so it can be towed.

Jim and Bev Earll | Mokelumne Hill, California

Answer iconPast dinghy guides are available for free at www.motorhome.com/download-dinghy-guides. The 2015 SRX is flat towable; I checked with Blue Ox and Roadmaster, and they both offer the equipment needed to tow your car. Each has a baseplate-finder section on their respective websites; those will outline what you need. Refer to your car’s owner’s manual, which lists recommendations including a 65-mph speed limit, starting the engine during rest breaks and proper shifting techniques. Keep in mind that you should also use an auxiliary braking device.

ABS Light On

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We bought a pre-owned 2007 Holiday Rambler Neptune. It is a great motorhome; however, ever since we drove it off the lot the ABS light has been on. After talking to the owner of the lot, we discovered the problem with the light had been ongoing before we even bought it. I asked the owner of the dealership and he said it’s not a problem and would only be of concern if we were driving on icy roads. However, we live in Washington state, where there is lots of rain. We are taking it back to adjust the air bags because the coach is not sitting level, so I’m wondering how important it is to require them to fix the issue with the ABS indicator light.

Jacque Pasa | Via email

Answer iconThe anti-lock braking system (ABS) is an important safety system, which takes over whenever skidding is detected and pulses the brakes to allow the driver to retain control. This can be on wet roads or dry, any time the coach needs to stop fast – not just on ice and snow. Your dealer is apparently trying to dodge responsibility because of the potential cost involved. Some parts are cheap, others very costly. I strongly suggest you have the ABS diagnosed with the correct electronic tester and repaired as soon as possible.

How to Determine Towing Capacity

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I am shopping for a motorhome and I have a concern about calculating the weight of a towed vehicle that is within the weight range of the coach. Every dealer is quick to point out the weight the hitch will accommodate. However, just because there is a 10,000-pound-rated hitch on a Class A motorhome, that doesn’t necessarily allow it to tow a 10,000-pound vehicle. I have searched several sites on how to calculate what a Class A will safely tow, but they all use various acronyms for the calculation and there seems to be little agreement on the correct way, or which acronyms to use to determine the weight any Class A can tow. It may be a good time to revisit the best way to calculate the maximum weight a Class A can safely tow when purchasing a coach.

Jerry Straw | Round Lake Beach, Illinois

Answer iconVery few motorhomes, other than large bus-type coaches, have a 10,000-pound towing capacity. Unfortunately, there is a lot of misinformation spread by dealers who should be knowledgeable about their products. Never use the hitch rating as the tow rating, as this could lead to serious overloading. Many motorhome manufacturers provide maximum tow ratings for their coaches; these are often posted with the specifications on their websites, and they are just a guideline. To determine a towing weight, you’ll need the gross vehicle weight rating (GVWR), which is the maximum amount the loaded coach should weigh, and the gross combination weight rating (GCWR), which is the maximum amount the chassis manufacturer recommends for a combination of the motorhome and trailer or dinghy vehicle (including necessary hardware). The difference between these two numbers will give you a starting point. From here, it’s important to weigh your coach, loaded for a typical trip, with passengers, and subtract that number from the GCWR; that will give you the accurate tow rating.

Temporary Brake Loss

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I have a 2002 Winnebago Brave 32V on a Ford F-53 chassis. I was in heavy bumper-to-bumper traffic when the brake pedal sank to the floor. Then both the ABS and brake warning lights came on. After a cool down and a few teaspoons of brake fluid in the master cylinder (it overflowed with just an ounce or two in each reservoir chamber), the pedal was fine and has stayed that way. However, the brake light and ABS lights remain on. I took the motorhome to the local Ford dealer, who read the codes (no fault found) and then reset the ABS. The brake light was still on, and 10 miles later the ABS light came back on. I’m a skilled mechanic and want to know how to proceed with solving this. The rig only has 50,000 miles on it, so I think the pads are fine. There are multiple replacement sensors according to sites on the Internet (center differential, left rear wheel, right rear wheel, right front, left front). How do I determine which one is faulty? Note – when the brakes were hot, only the rears were really throwing off heat and odor.

Jack Duich | Via email

Answer iconI think the brake fluid got so hot it boiled, and this caused expansion and overflow out the reservoir cap vents. This is a serious situation and needs to be addressed before the motorhome is returned to service. Very often this occurs when old brake fluid that has absorbed moisture from the atmosphere through the cap vents heats up. The fluid and system should be flushed approximately every two years, depending on dampness of climate. If the rear brakes overheated, even with only 50,000 miles of service, they must be inspected. The calipers should be carefully inspected to determine if any pistons are sticking on and not fully releasing. This could cause the overheating, and the pads and rotors may be damaged from the excessive heat. The regular brake warning may be triggered by the shuttle between front and rear systems, but should be diagnosed, according to the Ford shop manual. You really need a code reader to determine what’s wrong with the ABS; perhaps you should take it to a shop that’s more experienced. The dealer should not have released your motorhome with serious brake problems.

‘Chirping’ Sound – Tip

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I read the question in the May issue about a chirping sound in a Ford V-10 Minnie Winnie 31C. In my opinion, the sound is probably coming from the idler pulley on the serpentine belt. After sitting for a long period of time, the bushing will start to deteriorate and may need to be replaced. As a rule of thumb, when you replace the serpentine belt, replace the idler pulley at the same time.

Have a tech question?Charles Allen | Lansing, Michigan

Answer iconWe had several readers write in mentioning belt idlers as a cause, which is a good possibility. What threw me off was the description of the sound. All the idlers I’ve heard with bad bearings (not bushings) have produced what I consider to be a squealing sound. I think of chirping as more of an intermittent on-and-off high-frequency sound. In any case, the sound changes directly with engine rpm, not road speed, and since it occurs while idling, it can be checked and pinpointed easily.

‘Chirping’ Sound – Comment

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Regarding the letter in the May issue, I found that on our Class C on a Sprinter chassis, the valve stem extensions (necessary because of the tire-pressure monitors) protruding through the small hubcap openings were rubbing on the edge of the hubcap opening, causing a chirping sound. I only discovered this by accident when I took the hubcaps off to clean brake dust off the wheels. I have since slipped a piece of vinyl tubing over the valve stems. No more chirping sound.

Larry Weyand | Yakima, Washington

Answer iconThanks for sharing your experience Larry. We have had several comments on this subject, but yours is the only one regarding hubcaps. If the sound only occurs when you are moving and continues if you shut the engine off and coast, it’s in the chassis. Try driving slowly past an assistant on the side of the road, who may be able to pinpoint which area the sound is coming from.


Ken FreundRV DIYRV TechRV Tech Savvy

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