NOW I OWN A COACH. HELP! At one time or another every one of us has been a newbie. A babe in the woods. A novice. I am talking about this in the context of Prevost conversion ownership. There are few things that can be as daunting as being given the keys to your first Prevost conversion and watching the seller wish you good luck while he walks away. At that point you don t even know what you don t know. You are not alone. At any given time there are others just like you who also haven t got a clue about their new pride and joy. So what exactly are you going to do to avoid all the mistakes new owners make, to avoid spending serious money because of a mistake, and to protect your safety? The first thing you should do is learn your coach. Maybe you can bumble your way through the learning experience on your new well equipped car. You might even get away without any training on your new coach for a while. But sooner or later you are going to either end up learning that coach, or you are going to pay dearly for not learning. Some of the cost of not learning might even be increased risk to your safety. So let s start helping you by talking about safety. SAFETY. It is not an accident that safety finds its way to the top of the list a new coach owner needs to realize. Few of us routinely drive around in air brake equipped heavy large vehicles so one of the first things a new owner needs to do is develop an understanding driving a coach requires certain knowledge and understanding. The coach cannot be driven like you do the family car. You should not just hop in and turn the key and head down the road. First and foremost the coach needs to be at the driving height or road position. For this to happen the coach needs to be aired up. So start the engine and select the switch position that puts the coach at the height for driving. If the level low light is on it is not in the driving position and the coach should not be driven. While air is building and the coach is going to the driving height step out and check the lights. There are a lot of them and because the coach is so big and ponderous you want all of them working so when you step on the brake or intend to make a turn people can see via your lights what your intentions are and they can act accordingly. A light check is important to both your safety and that of others around you. If you are towing make sure the toad or trailer lights are also working. Please get used to making a light check a part of your pre-trip tasks.
Now it is time to check the brakes. Unless you possess a commercial driver license it is likely you may not even be aware your safety and that of others depends on good brakes and the only way you can be assured they will work properly is to check them. Drivers of large commercial vehicles are expected to do a standard DOT brake check every day before driving. Respect the fact you are driving a vehicle built for commercial use and you should be doing the same. When your bus is parked with the parking brake on and your foot off the brake pedal your brakes are applied at the drive axle and likely the tag axle by spring brakes and there is no primary or secondary air pressure beyond the brake pedal, which is actually a dual circuit air valve. The first step is to block the wheels so the coach cannot move. Shut off the engine. With air pressure on both circuits up to the maximum (somewhere around 120 to 125 PSI) release the parking brake. You should see one of the gauges indicate a slight drop in pressure and then stabilize. There is a standard for allowable pressure drop of a few pounds of pressure per minute. You can look it up on any state s commercial driver license handbook, but if you are leaking down, however slight the drop, you have something you want to have corrected. That leak will not repair itself. The next step with the emergency or parking brake released is to check the service brakes. Step down hard on the brake pedal and do not release it. Again you should see a slight drop in pressure on both gauges, but after the initial pressure drop the pressure should be maintained. Again a slight continuous drop in pressure is allowed but there should be none in a tight system. In both tests above if you see gauge indications of air pressure loss you have a leak somewhere in your braking system. I am not going to tell you that s OK, because it is not. You may be within legal limits as far as the leak down rate but there is still a leak. Next you want to continue the brake system test by checking the operation of the primary and secondary visual and audible alarms. Apply and release the foot brake rapidly. You will hear air escape with every cycle. When the air pressure gets down to 60 or 70 PSI you should see a warning light on the dash for each system and hear an audible alarm like a buzzer. This is your alert that you are losing air pressure in your primary or secondary brake systems. Finally with the parking brake still released, continue to cycle the foot brake on and off and at about 40 PSI the parking brake knob should pop up and the parking brakes should be applied. Start the engine. The final step in the brake system check is to observe that at an
elevated RPM the air pressure builds quickly. From 85 PSI to about 100 PSI at elevated RPM the time span should be around a minute for the pressure rise. With the lights and brake systems checked you should continue to check the coach prior to driving. The next critical items in my opinion are the tires. Check their inflation pressures and look for indications of problems such as sidewall cracking (due to age). Your tires need to be pressurized based on the weight they are carrying so it is a good idea to weigh each of the axles on the coach and then refer to the inflation pressures called for on sites such as this one. http://www.michelintruck.com/michelintruck/tires-retreads/load-inflation-tables.jsp It seems everyone has an opinion regarding tire pressures, but the folks that manufacture your tires must be considered the experts. Lights, brakes, tires. Oops, lets not forget belts and fluids. Check oil, coolant and power steering fluid levels. Take a look at the belts and make sure they are not frayed or showing signs of splitting or cracking. Don t forget the generator. Make sure moveable objects in the coach are secured. Make sure you have disconnected and stowed the shore power cord and the bays are closed and the antenna(s) are down. Did you latch the engine compartment doors? Are the mirrors adjusted? There are a lot of things you should be doing before you get underway and I would recommend a checklist. Make your own, or copy any of the examples you can find on various sites including Prevost Community. Now that you are on the road do you understand this is not your father s Oldsmobile? Our coaches are quiet, we sit high (fooling us into thinking we are going slower than actual speed), and other than aiming there is not much we need to do. Or is there? Lets start with the dash, the gauges and the annunciator lights. Unlike most of our cars our dash provides us with a lot of information. Some gauges are vital to our safety with the air pressure gauges being very important. The air pressure should cycle between 120-125 at the high side, and drop down to 100-105 on the low side. They should not cycle a lot without a reason. If they are cycling a lot and they were stable during the brake check you may have a suspension working very hard due to a lot of curves and bumps, or you may have an auxiliary air system leak. Whatever the reason just understand the air pressure gauges are telling you valuable information. We have a coolant temperature gauge and this one is important because a hot engine will destroy itself and your wallet. Every vintage coach has normal operating temperatures and if you do not know what they are or what to expect talk to other owners of your vintage coach to find out what temps are normal for yours. If you seek information on a forum, put your chassis model year in your signature line. Your
coach may be titled a different year so make sure it is the chassis year that is listed. You can start here to get all kinds of important information about your coach including how to read the chassis model year from the VIN. http://prevostparts.volvo.com/technicalpublications/en/manuel.asp Your gauges are also going to include others you might be familiar with such as oil pressure, RPM, speedometer, voltmeter, and turbo boost gauge. Again it is strongly suggested you find out what normal readings should be for every gauge and then when a reading is outside that normal range you can be aware something may be a problem before the problem gets serious and expensive. In almost all cases the gauges are the early indications you need to concern yourself with a problem. But we also have warning lights or annunciators. Some will be very new to you, while others will be what you are familiar with on your car. The link above is an amazing resource because through that link you not only can get access to wiring diagrams, pneumatic diagrams and other technical information you can call up owner s and maintenance manuals for your specific coach if you do not already have those manuals. If you do not have the various manuals for your coach you can read them on the above site. I recommend you bookmark them or print them. The importance of two of the annunciators cannot be overstated. All our computer equipped (DDEC) engines have sensors that constantly monitor and control various functions. There are three conditions which will trigger a stop engine light (SEL). They are high coolant temperature, low coolant level and low oil pressure. Once the SEL and check engine lights (CEL) come on simultaneously your engine will soon shut down. If you are in the outside lane of the Washington DC beltway traveling at a high rate of speed in heavy traffic when this happens you are in serious trouble until you can move the coach to a safe place out of the lanes of speeding traffic. Before you head out on your first trip, (or your next trip) learn where the over ride switch is that will keep your engine running for short intervals. If you cannot immediately get to the shoulder of the highway to a safe spot you are at risk and that switch will enable you to keep the engine running. Recognize the switch will only provide a short extension of time before shut down, but that might be all that is required to get you to a safe spot. We are talking about safety here and you and other drivers are not safe if you end up stopped and disabled in the lane of traffic. Find the over ride switch and learn from the owner s manual how and when to use it and its limitations. In any discussion about safety it would be an oversight if we did not cover how to
drive a coach. It may be possible to drive a coach like you do a car. You can certainly exceed any legal speed limit. You can tailgate. You can change lanes quickly. All of this is just like cars are driven. Just keep in mind there is one thing you will never do like a car. You cannot stop like a car. The average car at 60 MPH is capable of stopping in 130 feet and often less. Some cars can stop from that speed in about 100 feet. On your best day, dry pavement, level ground, and not counting the distance traveled during your reaction time your coach will stop from 60 MPH in over 300 feet. In a full panic stop you will still take about 3 times the stopping distance of the car in front of you. Increase the speed and the distance to stop goes up exponentially. In other words you now are sitting behind the wheel of a 50,000 pound weapon that places every car around you at risk. Please drive it accordingly. If the image of what can happen during high speed tailgating doesn t frighten you to back off, think about what is going to happen if you have a blowout. THE HOUSE ELECTRICAL SYSTEM. Our conversions are actually the product of two companies. One company is Prevost who builds the chassis. The other company is the converter. This company (the converter) took a shell and built a house in it. This house is a self contained apartment that just happens to be located inside a bus. Because it is self contained and because it can be used in a variety of situations it is not completely like a real house. It has systems and devices unique to a conversion. What I consider the heart of the house is its electrical system, or more precisely its electrical systems. Just like the chassis has an electrical system and provides gauge(s) to monitor the health of the system, the house also have electrical systems and will have gauges or dials or panels that offer you the opportunity to monitor the systems. As an owner you have to first learn and understand that you likely have 12 volts direct current, maybe 24 volts direct current (12VDC and 24VDC respectively) and 120 volt alternating current (120VAC). In this context do not interpret AC as meaning air conditioning. The 12 and 24 volt DC systems get their power from the house batteries (as opposed to chassis or starting batteries.) If you do not know the difference between the two, look for and locate where each set of batteries is and learn where their respective main shut off switches are located. But in addition to DC powered circuits that are typically used for such diverse components as lighting, valves, pumps, and phantom devices such as alarms, monitors (CO), and to power relays our coaches have AC powered circuits. The AC circuits may include such things as outlets, refrigerator, TVs, air conditioners, water pump, and awnings and shades. There is no standard and
each converter sets up systems according to how they think they should be built. For this reason no one that owns a Marathon conversion for example is likely to understand how a Royale has been set up and how their systems work. Keep that limitation in mind when you post a question on a forum. What is a correct answer to a question relating to a Marathon, may not be correct for a Liberty. So the first step in learning the house so you stay out of trouble is to find others who own a conversion similar to yours and who might be willing to offer guidance and help. If you have the owner s manual as prepared by the converter that is a valuable resource, but equally valuable is another owner who knows his coach. Over the years I have found the way most new owners get confused and then in trouble is they do not understand how a device gets its power and why. Not only understanding what the power source is for each device, but understanding how all the power sources actually work together is important. Keep in mind however that since the conversions are self contained the house batteries play a critical role in keeping the house systems working. There is no way to draw a simple word picture of our electrical systems. One of the problems is not all electrical systems are built using the same design. But is it important to remember that regardless of how the electrical systems are designed, there is one thing common to all conversions. They all have house batteries. And unless those batteries are in good working condition it is likely the problems that arise are going to be multiple and confusing. So as a new owner, learn how to protect the batteries from discharge, learn how to properly turn off the power from the batteries without damaging anything, and how to monitor the battery charge so when they fall below a certain voltage they can be recharged. Once you get past the complexity of learning how your batteries are turned on, turned off and charged shift the focus to how to identify and turn on or off the electric power to every device. At some point or another you may want to turn off components for power management (more on this later), or to service something, or to shut something down that may be having problems. Finally in this very brief section on electrical systems try to understand your inverters, how they work, how they are controlled, and how to change their operating parameters. An inverter as many of our coaches are equipped is actually an inverter, charger. When there is not 120 volt AC power source such as from shore power or the generator, the inverter takes power from the house batteries and changes the 12 VDC or 24 VDC power to 120 VAC to power those 120 volt devices that are on the inverter circuits. When the coach has 120 VAC power available either from shore power or because the generator is running the inverter changes to a battery charger
and maintains the charge on the house batteries. It bears repeating that understanding how the converter set up your coach is very important because while we all know and recognize the components used in the electrical systems, they may not be set up the same. One of the biggest problems new owners have is the lack of understanding when they have a problem. And when this lack of understanding relates to the electrical systems often the outcome is a perfectly good set of batteries will be ruined. The payback for taking the trouble to at least understand the electrical system and especially how to protect the batteries will be beneficial to your wallet and worth the effort. THE HOUSE PLUMBING SYSTEM Like the electrical system each converter has their own way to provide for the plumbing needs of the house. What they all have in common is a water holding tank, a pump or multiple pumps, water faucets, toilets and showers, and finally a waste holding tank. As a new owner it is probably not necessary to be able to diagram the plumbing system, but it is helpful to know where the components are, how they work, and the system operating methods. For example some water pumps are simple small DC voltage pumps with built in pressure switches and check valves. Others might be relatively large DC or AC powered pumps that have some internal computerization that might need some understanding. Does it make sense to know at least the basics before you need to shower or flush the toilet? Speaking of toilets there are a number of types, some only requiring a step on a pedal and allowing gravity to do the rest, to somewhat complex toilets that require pressurized air and may have a dedicated air compressor. I will vote for learning about how my toilet operates as being a relatively important thing. No need to say more. Some water systems have what we can all recognize as a hot water heater, yet others may use a heating system called AquaHot as the source for heating water. Whatever method to heat water has been employed by the converter it is valuable to learn what it is, how it works and if there are multiple ways of heating water. Some water systems have filters, water softeners, and or expansion tanks, all of which require some form of maintenance. If you do not have the information regarding those items installed on your coach it is worth the effort to go on line to seek out the owner s manuals for them. As a final thought on plumbing systems I would urge that before you are in trouble, try
to learn the location of all of the various shut off valves for the fixtures in the coach. If you experience a leak or if water will not quit running you need to be able to turn off the water supply to that fixture. Some coaches have manifolds with all water supply lines and valves clearly marked and in one spot. Others may locate the valves near the actual fixture. Regardless of how the converter set up the coach it is always best to learn where the valves are located before you really need them. THE HOUSE HEATING AND AIR CONDITIONING SYSTEMS (power management) This topic is actually the least important. If as a new owner you cannot keep the coach cool or warm it makes you uncomfortable, but it doesn t have the potential to do any damage other than sweat stains on your shirt. They are included here because power management comes into play and most new owners have to understand our coaches usually can draw more power than what might be available. There are very few owners who have not tripped a circuit breaker on their shore power outlet box. As the sophistication of our coaches has increased so has the need for greater amounts of power. We are all likely to find it easy to exceed the available power with the various devices we have on our coaches. This almost always happens when we need the greatest amount of power during a summer heat wave and we want to run all of our air conditioners. The receptacles in the typical campground power box usually have a 20 amp, 30 amp and 50 amp receptacle. That starts the confusion because the 20 and 30 amp receptacles are limited to those current amounts at 120 volts. But when we plug into the 50 amp receptacle we actually are limited to 50 amps per 120 volt leg, or a total of 100 amps on both legs. There is a further thing that should be noted. Whatever the available power is described as being, the real full load value you can be assured of is 80%, or 16, 24, and 40 amps per leg respectively. If you exceed those values you can plan on having the shore power breaker trip. So how do you cope when you need to draw a lot of power? The only way is to turn off all devices that you can live without. Let s pretend you decide to run all four air conditioners. For discussion purposes we will say each air conditioner draws 13 amps at 120 volts so it is likely you will start out with 26 amps on each of the two legs of your 120 volt electrical system. That allows you to add up to about 14 amps of load per leg. To manage your power needs you first need to learn how much current each circuit draws, and which leg each circuit is on. Every circuit in your electrical box will add a load, some constant, and some intermittent. You need to understand that also. If I have to live with a limit of 40 amps per leg and I want to run all four air
conditioners I would make sure my house batteries were fully charged so I can leave my inverters on. I know from experience my inverters with no lighting load and no apparent use of battery power are going to add about 3 amps per leg. Now I am up to 29 amps per leg. I sure need my refrigerator to keep things cool and I know that draws 6 amps (for example) so now I have one leg at 35 amps. I want my water pump turned on so I know that takes a few amps when it runs so assuming it is on a different leg than the refrigerator I have both legs now capable of drawing 35 amps. I will probably leave all other switches off because now I can use some lighting which will increase the inverter current draw. Later when it cools down I can turn off an air conditioner or two and turn my HW heater back on, my auxiliary air compressor and my TV circuits. The point is your understanding of the electrical systems is important for a variety of reasons because unlike a typical 30 foot Winnebago we cannot run all of our electrical devices and not trip shore power circuit breakers. If more power is needed beyond what shore power has available, consider running the generator. Almost all of our generators have been sized so we cannot overload them. TIDBITS (things we usually ly learn the hard way) Learning a new coach can literally take days and then the training can be compared to force feeding. The training is coach specific since all of our coaches are different, But here are some things that are beyond normal training that are good to keep in mind. If your coach will not go back to the driving position even when the switch is in the right position the problem may be as simple as replacing a solenoid valve coil on the center valve in the 5 solenoid valve manifold located in the steer compartment. Learn where the manifold is and if the coach will not go to the driving position swap the center coil with any other. Of all the phone calls I get from owners this has been the most common problem. Think about alternate ways to deal with a problem. We have a lot of redundancy built into our coaches. For example if the alternator to the chassis or house quits working most of us can start the generator and use either the inverters or a chassis battery charger to keep our batteries charged. Keep a list of contact phone numbers and at the top of the list should be Prevost and your coach s converter. If you have internet access don t hesitate to cry for help on a
forum. It is amazing how quickly folks will respond. Charlie s Bait Shop and RV Repair may be able to help you when you are in trouble, but don t bet on it. Don t leave your coach with anyone unless you know they know how to care for your coach when it is not in use. Make them show you their power outlet or demonstrate to you their knowledge of how to prevent your batteries from going dead. Don t leave your coach with anyone. (You may be trusting. I am not) There are three things you should never be without on your coach: A way to check tire pressures. A voltmeter or multimeter you know how to use. An IR temperature reading gun. If you get an annunciator light on the dash for hi or low voltage or battery imbalance use the voltmeter or multimeter to read the input voltages at the Vanner electrical monitor located above the chassis batteries. If the electrical values are within the proper range just unplug the output terminal to extinguish the dash light and replace the monitor when able. A word of caution While the monitors have had a spotty reliability, they are there for a reason. Make certain there is no real problem before disconnecting the monitor and proceeding down the road. If in doubt shut it down and get help. If it is hot and you do not have full bus over the road air consider running the generator and turning on all air conditioners. Keep the entire bus cool and it makes it more comfortable for you and easier for the air conditioners to do their job. You may be able to run one or two air conditioners from your inverters, but you are really putting heavy loads on your coach alternator(s). It needs repeating..your gauges often predict problems and locate problems. Pay attention to them, learn what is normal, and anytime a gauge departs from normal do something. None of our buses will repair themselves. If something is changing something is likely going wrong or about to go wrong. And that is when you are in the middle of nowhere and end up at the mercy of Charlie s Bait Shop and RV Repair. Take care of problems before they get serious and while you have options. That is the best reason I can think of for learning your new coach and its systems. Jon W. Wehrenberg 7/9/2012