Today we are going to discuss how and why to perform a voltage drop test. Hopefully you’ve taken the time to read our Automotive Circuit Testing article and are familiar with the basics when it comes to testing automotive electronics. We’re about to take it a step further and explain the benefits of checking voltage drop across component connections, connectors and terminals. Believe it or not, it’s possible to check a power supply circuit for voltage and show a good reading of 12 volts, but still have a faulty circuit. You could check that same line for resistance and show an acceptable reading of .2 ohms, and again still have a faulty circuit. Talk about throwing a wrench into the works! How can that be you may be asking yourself. Well, there are a few circuit problems that can contribute to this testing concern. A chaffed line that only has a couple of strands of wire will pass a continuity test, but certainly won’t be capable of carrying any real current. Poor connections, loose crimps and corrosion issues may also test out fine on a typical voltage or resistance check, but when a load is turned on and current is needed across these circuits they likely won’t perform as expected. Any increase in circuit resistance, even a very small one, is going to create problems. This is where a voltage drop test is used to pinpoint the source of the concern. Voltage drop tests are most effective with high amperage circuits, and are often used when diagnosing the starting and charging systems in automobiles. As such we will cover testing both systems in today’s article. A voltage drop test is done on a “live” circuit, meaning that you must create a load in the circuit while taking your readings. Voltage will always follow the path of least resistance. A circuits wiring and connections should have next to no resistance and as such, all voltage should be used through the load. The “load” is the component using the power, such as a light, starter or blower motor. If a circuit has excessive resistance, it prevents the wire from carrying sufficient current under high load conditions. When you place your meter “across”, or in parallel with the circuit you are testing, you are providing another path for the voltage to travel. If there is excessive resistance then your meter becomes “the path of least resistance” and you will register a voltage reading. If the circuit is functioning properly all voltage will pass directly to the load and your meter will register an acceptable reading. “Acceptable” for most circuits is less than .4 volts, although .1 volts or less is preferred. Some starter circuits can allow up to .6 volts during a voltage drop test. Anything higher than these values indicates a need for repair. Repair usually includes cleaning corossion from connections, repairing faulty terminal crimps or tightening fasteners and connectors. It is also possible that the wire guage is inadequate for the size of the load. In this instance a “heavier” or thicker wire is needed. So that covers the basic theory behind a voltage drop test. Now let’s apply this knowledge to a couple of practical applications so we can get a better idea of where to place our test leads and how to approach a complete system. Let’s start with a basic starting system. To test this system you’ll need to check for excessive resistance throughout the circuit by measuring voltage drop at the battery, cable connections and starter. These readings will need to be taken while the engine is being cranked. Cranking time of around 5 seconds should be adequate for solid test results. Always remember to disable the engine so it will not start while doing these tests. If your vehicle has an inertia or fuel shut-off switch you can trip this. You could also disconnect the coil or ignition circuits or remove the fuel pump or computer relays. So let’s get started. Place your DVOM (Digital Volt Ohm Meter) on the 20 volt scale. First check battery voltage by placing your meter’s positive lead on the battery’s positive post ( the actual post, not the clamp) and the negative lead on the negative post. We need a minimum of 12 volts to continue testing. Next, leave your meter connected and take a reading while the engine is cranking. Record this voltage reading. Now connect your postive lead to the battery terminal stud on the starter and the negative lead to the starter housing. Again, crank the engine and record the voltage reading. If the voltage reading at the starter is not within 1 volt of battery voltage then we have excessive voltage drop in the starter cricuit. We will isolate the cause by testing out the individual parts of the circuit. To check for voltage drop we can turn our meter to the 2 volt scale, or leave it set on auto if your meter is so equipped. We can check total voltage drop in the starter circuit by connecting our postive meter lead to the positive battery post and the negative lead to the battery terminal stud on the starter and read the voltage while cranking the engine. Anything over .6 volts is an excessive voltage drop and can be isolated using the following steps. First, check battery post to cable connection: positive meter lead on battery positive post, negaitve lead on battery’s positive cable clamp. Crank the engine and note the reading. A good connection should have zero voltage drop. Second, check the positive cable: positve meter lead on positive battery clamp, negative lead on starter terminal connector. A good cable will show a voltage drop of .2 volts or less while cranking. Third, check the starter connection: positive meter lead on positive battery terminal on the solenoid, negative meter lead on actual starter stud. A good connection will have a voltage drop of near zero volts. Now to check the negative side of the circuit. Total drop on the ground side should be .3 volts or less and can be checked by placing positive meter lead on starter housing and negative meter lead on battery ground post. Take your reading while cranking the engine, and be sure your connection at the starter is solid and clean. If total voltage drop on this side of the circuit is excessive, complete testing at all connections in the same fashion as the positive side of the circuit. Check the following: between battery post and clamp (zero voltage drop), cable end at battery to cable end at engine. (.2 volts or less), cable end at engine to engine itself (near zero voltage drop), and finally between starter housing and engine block (.1 volts or less). And that wraps up the starter circuit checks last move onto the charging circuit tests. So let’s get started! First check the entire positive side of the charging circuit for excessive voltage drop. Hook your meter’s positive lead to the alternator output stud and your negative lead to battery positive post. Run engine at 2,000 RPM with all lights, blower motor, radio etc. on and check voltage reading on meter. Leave the rear defroster off during this check as it may create a unusually high read. An acceptable reading is .5 volts or less. If you have an out of spec. voltage drop, check connections at alternator and battery as well as for an use of undersized cable. Check the negative side for the charging circuit the same as the positive with your meter’s negative lead on the alternator case, or ground strap if equipped, and the positive lead on the batttery negative post. Voltage drop on this side of the circuit should be .2 volts or less. If it’s not you know what to check and how to check it! And that wraps up our voltage drop article. I hope you have found some useful information. This is the kind of info that can save you on those hard ones. Ones that you test by the book and everything passes, yet you know there’s something wrong! Good luck and enjoy the day! News source: Engine-Light-Help

Like any specialized field, auto repair has its own unique set of abbreviations. Used by professionals, the abbreviations can seem to create a completely different language. This can be frustrating for car owners who may not understand what’s being said and who find themselves too embarrassed to ask questions on their meaning.While you should always ask any question that pops in your head especially when dealing with something as important as auto repair, you can ease the embarrassment by studying up on some of the more common auto repair abbreviations.Now many car owners will encounter only specific abbreviations, usually ones dealing with parts. These abbreviations will probably be used when discussing the replacement of damaged items of your car and may even show up on your bill.OEM- Original Equipment Manufacturer. This simply means that the part is certified new by the manufacturer of the car. This is important for those owners wanting only new parts and that need an assurance of that fact.QRP- Quality Replacement Part. When mechanics use “QRP” it is used as a euphemism. What this really means is that the part is an aftermarket part.A/M- Aftermarket. An A/M is a part not made by the manufacturer of your vehicle.Now other abbreviations will be used when dealing with the actual maintenance of the vehicle. These abbreviations are second nature to many mechanics who may use them absent mindedly even to customers.A/F Ratio- Air/Fuel Ratio or Air to Fuel Ratio. A proper A/F Ratio is needed to properly start the car.CAT- Catalytic Converter. Back in the 1970s the United States started strengthening EPA standards concerning internal combustion engines. The CAT is used to turn toxic by products into something a little less toxic.DFI- Digital Fuel Injector. Fuel Injectors replaced carburetors back in the 1980s. The DFI relies on high pressure to mix the fuel and air where carburetors used low pressure.DTC- Diagnostic Trouble Code. As the name suggests, the DTC helps to identify any problems. The mechanic reads the DTC with the help of a scanner tool. The DTC consists of 5 digits.FIPL- Fuel Injector Pump Lever. This piece of equipment insures the continued operation and performance of the fuel injector pump. The fuel injector pump is responsible for getting the fuel from the tank to the injectors. This is critical for the vehicles continued performance.GPS- Global Positioning System. These systems are becoming more and more popular and are even featured in many of the newer model cars. Should there be something wrong with the GPS then you need to make sure that the mechanic understands how to work on it.hp- Horsepower. Horsepower is a measurement of power and is usually used to refer to trucks and some SUVs.Now, there are certainly numerous other abbreviations beyond what is listed here which you will no doubt hear while having your car service It is always a good idea to learn at least a handful of abbreviations before heading to a mechanic. A little knowledge goes a long way, after all, and by displaying some know how you will be able to understand the lingo and jargon of the auto repair shop. News source: Car Service

Men vs. Women: The Oil ChangeNo matter what side of the chromosomal match you stand on, there’s no denying that men and women have different ways of going about the same task. There’s a reason for the old tale of the man refusing to ask for directions — it’s true. Never is the difference more apparent than in the case of the oil change. Here’s a play-by-play of the man-vs-woman oil change.Women: Stop at Starbuck’s on the way to the Super-Lube, order a decaf skim latte but go for a dab of whipped cream because you’ve been good. Sit in waiting room watching CNN and sipping delicious coffee drink. Twenty minutes later, pay with AMEX for the Sky Miles and leave with the job done and the whole day ahead of you.Men: Go to AutoZone and drop $47 for oil, a new filter, kitty litter, and a talking tire gauge (damned impulse-buy rack gets you every time). Go home, drive car onto oil change ramps and change into your college game-day shirt, which now feels like a size extra-medium. Discover you forgot to empty your last oil change from the oil container, so drive to back of Super-Lube and beg them to take your old oil. Get dirty look from 17-year-old punk and tell yourself what you’d do to him if he was 18. Drive home, back on ramps, then detour to fridge for a cold one. Gather tools and slide newly-emptied recycling container under oil pan. Realize you grabbed the wrong spanner to remove the oil drain plug, so you decide to use Vise-Grips since you’re already on your back. Unscrew drain plug, but fumble with it and soak forearm in not-quite-cool-yet motor oil. Lose drain plug in recycle container since you removed the screen to use for your failed bio-diesel lawnmower experiment. Have another cold drink to mourn failed bio-diesel lawnmower experiment and wait for oil to drain from engine. Look for oil filter wrench, but give up and stab filter with a screwdriver, then twist it off. Install new oil filter, making sure to apply a thin layer of new oil to the gasket. Almost done, remove oil cap and pour first quart into engine. Quickly realize your forgot to replace the oil drain plug. Race to reinstall plug with wrong wrench and skin knuckles on motor mount. Bang head on A-arm in reaction. Shoot across driveway on creeper and begin cussing fit. Throw wrenches into yard, then crawl through flower bed trying to find correct wrench for oil drain plug. Time for another cold drink (yeah, we mean beer). Tighten plug and add remaining oil. Watch wife pull into driveway with the smug look of efficiency on her face. Carry groceries into house. Smile, she bought more beer.Of course, all of that can be avoided by checking out our tutorial on changing your own oil. There’s no substitute for good preparation. News source: About Auto Repair

A car ding repair is easy to do if you have a good auto ding repair kit. Such repair kits are not so expensive; about $30 and it’s really easy to used. Such automobile ding repair kids can be purchased at most stores selling car parts or car accessories. The task you have to do is to pull or remove glue from the surface on all panels of the vehicle and most of these cheap ding repair items for sale today are really working for this purpose if the dents or dings are not too big. For small and medium dents or dings, ding puller devices provides a simple, cost efficient removal. Fortunately there is no need to access the underside of the panel.We see a trend today that more and more vehicle manufactures are using light gauge sheet metal in the construction of vehicles. In fact, it is not difficult to dent many new cars by simply leaning against them. The nice things about these dent/ding out, glue puller kits are that they give the do-it-your-selfers and car amateur enthusiasts a professional option to expensive dent removal services.There are also different kinds of ding or dent repair kit and each of them offers a tool for specific damage. So you must know which repair kit you need for fixing your specific problem. This is no big deal however, because the only thing you have to do is to tell the sales person in the auto part or accessory store what you’ll need to do and he or she will find the dent fix kit for your needs. To cover yourself completely, you can buy several of them, thus having a tool for any ding or dent problem your car might incur. If you purchase three different ding or dent fix kits, you’ll have what you need for all types of dent repair.How to use these kits? Here is what you do:apply a bead of glue to the pulling nibaffix the nib to the lowest area of the dent you’re going to fixthe ding repair tool slips over the threaded studa wing nut tool is threaded down pulling the metal upas soon as the dent is pulled out, a couple of drops of a release agent that normally is included in the kit is applied to the glue and the pulling nib will come right off. These dent fix kits are inexpensive and easy to use and they will not damage your factory finish. News source: AUTOTIPZ

Spark plug wires are pretty durable. They aren’t a moving part so they don’t wear out too often. A careful inspection of your plug wires can avoid any problems.The only thing that can really go wrong with a plug wire is a break in the insulation. The insulation (the rubber on the outside of the wire) keeps the electricity where it needs to be so it sparks on the inside of your engine, not someplace else before it gets there. If the insulation is cracked, the spark will jump off the wire, or arc, onto something metal under the hood. An arcing plug wire can cause a weak spark or no spark at all in the cylinder with the bad wire. This makes your car run rough and can affect your gas mileage. It can also cause unburned fuel to pass into the exhaust system where it can harm your catalytic convertor. There have even been stories that involve both a fuel leak and an arcing plug wire, resulting in a fire! It can happen.A good time to check your wires would be while you change your spark plugs. So do a quick inspection and save yourself some headache. Here’s how:With your engine off, start at the distributor end of the plug wire and work your way toward the plug end. You’re looking for anything that is not smooth, pliable rubber. Bend the wires slightly to be sure no cracks appear. Check the boots at the distributor end of the wires to be sure they are not torn or cracked. Finally, check the wires at the spark plug end one at a time by pulling it off the plug and inspecting the end for any tears or cracks. Also look to be sure there is no burning or darkening of the end. If you find any damage, it’s time to buy a new set. They can be as little as $20 or as much as $100+ for a set depending on your application. It’s worth the cost, though. A bad plug wire can be a little monster, it can even trigger your Check Engine Light. News source: About Auto Repair News source: About Auto Repair

Wallets are getting tighter these days. Even for those of us who aren’t affected by economic woes, the price of gas will have you down right squinchy! A recent article quotes one shop owners saying his regular maintenance business is down because car owners are deciding to hold off because they are spending so much on gas. We know the gas prices are killing you, but don’t skimp on your regular maintenance! It may seem like you’re saving money, but maintenance is what keeps your car out of the shop. Skipping important maintenance jobs will end up costing you more money in the long run, and that doesn’t make much sense at all. So what’s the answer? Do it yourself! Most regular maintenance jobs are quick, easy and inexpensive. We can show you how to get them done, so you have no excuse. Performing your own scheduled maintenance can save money in many ways, but you’ll also be getting to know your car or truck better. This means you can catch problems before they get out of hand and you’ll be able to communicate much better with your mechanic should something need serious repair. News source: Auto Repair.com

You can get car auto repair questions answered in many places around the Internet. I myself visit several, when I have time; I also do evaluating for several. There is a ton of bad advice on the net, remember anyone can jump on most sites. That is why GreenFlagAuto has a Pit Crew. They are screened for repair knowledge and most answers I screen or do myself. I think this has prevented many from joining the Pit Crew. We are always looking for more help, if interested send me an E-Mail. I would rather not answer an inquiry than have misinformation on our site.I babysit my grandkids so on some days I have a lot of time and some days I don’t but I try to keep up and keep the site fresh.I know my advice is not always correct but I do my best to be sure it will do no harm to either you or your vehicle.Remember asking a mechanic or tech for advice is like asking which oil is the best you are going to get several different viewpoints.

Houston is no place to live without air conditioning. When one man’s A/C system took a dive, he was quoted a whopping $1200 to repair it. He was perturbed at the estimate, but University of Houston student Scott Dawson kept his cool. He wasn’t even sure how long he would keep his car, so the thought of paying $1200 wasn’t settling well with him. That’s when Scott shifted into high gear and set out to find a better solution. Instead of seeking an elaborate workaround for the car’s A/C system, he employed the faithful K.I.S.S. (Keep It Simple Stupid) system and drew up a plan for cool air that was a real money saver. Scott bought one of the smallest room air conditioners and mounted it on the roof of his car. He cut a hole in the roof to pipe the cool air right into the cockpit. To power the unit, he used what’s called a voltage inverter (a unit that converts DC power into AC) wired directly to his car battery and plugged the wall unit right in. It worked. Scott now has cool air blowing right on his head while he braves Houston’s high temps in traffic. His fix cost around $400. Sure, it’s not in any way permanent, and I wonder what would happen in a serious rain storm, but you have to applaud his ingenuity. News source: About Auto Repair

Spark plug replacement is becoming a problem as we run our plugs 100K; many times they cannot be removed due to a carbon build up. To remove them back out the plug a ¼ turn and liberally apply a carbon removal chemical preferably one with some lubricant. I use sea foam but there are better products with more lubricating properties, most from the Manufacture, let it sit for 15 minutes and then try again to remove the plug. It will be hard to turn if to difficult back it out as far as possible and then tighten and loosen until it frees up. Do not use more chemical as it may hydro lock the engine. If you due break off the plug there are several excellent tools to remove the broken shell.

With new cars and trucks increasingly complex and computerized, repair shops need access to highly technical information and software. Everyone agrees on that. But one group of industry associations wants the government to make sure automakers provide the technical information and tools to everyone, while the other side argues for trusting the auto industry to make the information and tools available under a voluntary agreement. As such it is a battle between those incompatible ideals – equality and liberty. The pro-equality group argues that auto manufacturers provide full diagnostic and service information to their own dealerships, which make some 50 percent of their profits from their service departments, but not to small independent repair shops, which get information that is either limited or late, or both. This group advocates passage of the Right to Repair bill that would require automakers to provide the same information and tools to independent shops and consumers that it provides to the service centers at their dealerships, with the Federal Trade Commission providing oversight. The act was last introduced in the U.S. House by Rep. Joe Barton, R-Texas, as a consumer-rights bill in 2005 News source: ProJo Meanwhile, the pro-liberty group argues that the information automakers currently provide under a voluntary industry agreement is adequate and timely, and that having the government involved through legislation would result in unnecessary bureaucracy. “It’s a philosophical difference; that’s how I would rate it,” said Steve Johnson, president of Number One Tire in Warwick and vice president of the Rhode Island chapter of the Automotive Service Association, which argues that automakers do provide the necessary information on a timely basis for affordable prices. He said the independent repair shops typically do not see new vehicles, which are serviced by the dealerships, and argued that independents have access to all the information they need through the National Automotive Service Task Force (NASTF). The NASTF is a collaboration between the service, equipment and tool industries and the auto manufacturers that was established in 2000 to provide technical information to repair technicians. The ASA signed up with NASTF in 2003. “The information (text service bulletins and software updates) is available,” said Johnson. “It’s not often that we don’t get it.” Stan Morin, president of New England Tire in Attleboro and Warwick and national treasurer and past president of the Alliance of Automotive Service Providers, disagrees. “The difference is this,” he said. “There is no good reason for the car manufacturers to continue in this process.” As he sees it, Johnson – who is a friend – is too trusting, relying on a voluntary agreement by the industry not to favor their own dealerships. He cited a 2002 agreement between automakers and repair shops in Europe that went awry, resulting in the European Commission getting involved and forcing four manufacturers – Fiat, General Motors Worldwide, Toyota and Chrysler-Daimler – to accept a fine of 10 percent of their sales if they were found to be favoring their dealership repair shops. He said if the European Commission had to get involved to that extent, why trust the automakers on this side of the Atlantic? “We are willing to pay for the information, but we want it to be identical to the information that the local franchises are getting,” he said Morin cited an example of purchasing a 25-page service bulletin from one manufacturer only to find out that the dealership was armed with a 41-page bulletin about the same subject. “If there is a page 26, I want a page 26,” he said, let alone pages 26 through 41. The AASP supports the federal Motor Vehicle Owners’ Right to Repair Act, which would prevent manufacturers from withholding information necessary to diagnose problems and service or repair vehicles from owners and repair facilities. Other organizations supporting the bill include AAA, the Automotive Aftermarket Industry Association and Service Station Dealers of America. They argue the bill would prevent an auto repair cartel through exclusive access to necessary information, increase competition and reduce auto repair costs. They add that it would also protect the kind of trusting relationship that consumers develop with their local repair shops, which are also often cheaper and more conveniently located. Morin told of his 84-year old mother-in-law who wanted to have her vehicle serviced at her neighborhood service station – “the owner is her former paper boy” – but who was told by the dealership that “we are the only place where you can get your car fixed.” He said it was not currently possible to complain to the Better Business Bureau or the office of the Massachusetts Attorney General because there is currently “no functioning law.” But he said a state Right to Repair bill has been introduced in Massachusetts and foresees a push to establish one in Rhode Island if Massachusetts makes it law. On the other hand, industry groups such as Johnson’s ASA and the National Automobile Dealers Association stand by their agreement with carmakers to provide technical information and tools. They argue that the Right to Repair Act would affect manufacturers’ ability to control the quality of work on their vehicles and lead to unnecessary monitoring by the Federal Trade Commission. They are also concerned the bill might require the release of proprietary information. Indeed, they argue that independent service shops as well as vehicle owners already have the right, through a voluntary agreement following a ruling by the Supreme Court, to access the diagnostic information and tools (read software) needed to maintain their cars and trucks. And perhaps most of all, this group has a distrust of government involvement and regulations. “There is no need to regulate the information that is coming out,” Johnson said. “It would be a nightmare.”