MAKING GOOD CONNECTIONS BY SAM BELL

Repairs or additions to a vehicle’s electrical system are necessary from time to time. The idea is to leave them when you’re finished as good as or better than how you found them.

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Photo: Thinkstock

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everal years ago, a client shop sent me a problem car they had been unable to fix. It was an early-aughts VW suffering from severe misfires. The spark plugs were new and the coils had already been updated to the latest version. Their lead tech had checked and rechecked the related wiring harness and found nothing amiss. The injectors had been cleaned, and the intake system smoke-tested. Fuel pressure and volume were within spec. A new MAF and oxygen sensors had been installed. The misfire codes still named each and every cylinder as a culprit. As always, the diagnostic process starts with verification. Sure enough, codes from P0300 to P0304 showed as active, and the engine was rough at idle. Following our standard practice, ace technician Joe Sandow set out for a brief ride. About halfway around the block he realized that the radio, an aftermarket unit in the dash, was still on, though muted. He turned the volume up to verify normal function, then tried to turn it off. (We find that listening to the radio prevents us from hearing the car clearly.) A few button presses eventually reached the source menu, and he turned the unit off. The misfiring immediately ceased. He drove a bit more, and the misfires remained at bay. He turned the radio back on and the misfiring resumed. He repeated this sequence a few more times and became convinced that this was no mere coincidence. Turning the radio on caused the misfires to resume; turning it off halted them consistently. Experienced VW technicians know that the factory radio unit of that era is a node on the vehicle’s CAN bus, which carries communications shared by various modules. The aftermarket unit, which we subsequently learned had been installed by the driver’s boyfriend, was not compatible with the factory wiring, at least not in its present configuration. Hundreds of dollars in parts, dozens of man-hours of work at our client’s shop, and the answer turned out to be nothing but a turn-off! Of course, not every electrical problem is as easily or as quickly solved. My goal in this article is to share some basic techniques that will help you avoid

creating these types of problems in the first place as you help your customers customize their vehicles with any of a variety of aftermarket electrical devices. A search of Motor’s archives confirms what you already know: Starters, generators and batteries have become more reliable and longer lived, but “electrical problems” of one sort or another have multiplied as electrical content has grown. My primary focus in this article will be aftermarket electrical installations, but, as usual, there are some basic considerations we need to address first. As any architect or civil engineer knows, a building or a bridge can be only as strong as its foundation. For that reason, we’re going to start by looking at batteries and terminals, because they are the foundations of a healthy electrical system. A good battery is central to the electrical system. In most cases, the factory correctly sizes the original battery adequately to meet a vehicle’s electrical needs even as it ages. A starter may well consume more current and/or may need to do so for a longer time to crank up a vehicle with 150,000 miles on it than it did when the vehicle was new. So by the time the vehicle shows up in your bay, its battery may not still meet those original requirements. And, importantly, add-on equipment may have been installed, so the original specs may no longer be adequate. Step one, then, must be to answer these three questions: 1. Does this battery at least meet or exceed the original specifications? 2. Does this battery still meet its own specifications? (If it doesn’t, it’s time to replace it, even if it still surpasses the vehicle’s original specs.) 3. Is this battery adequate to meet the demands being placed on it? This includes assessing the battery’s current state-of-charge (SOC). If the battery needs to be recharged, you’ll have to recharge it, replace it and/or supplement it with a jump box before proceeding with any further testing. Step two is to make sure that whatever power is in the battery can get out to the rest of the vehicle when and as it’s needed. The following questions may be elementary, but years of experience have taught me they cannot be overlooked or taken for granted. November 2015

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Photos: Sam Bell

Making Good Connections

This underhood Power Distribution Center features two B+ studs. The one on the left leads directly to the battery, while the one on the right supplies power to the power steering control module via a hefty 80A main fuse. Since you don’t want to lose the power steering, your power feed must be pulled directly from the B+ junction, but be sure to provide an in-line fuse nearby. Or maybe, if your needs are smaller, you could use one of the vacant fuse holders, already conveniently wired for 25A each.

•Are the battery terminals tight? Give them a twist. If they move, work is needed. •Are the terminals clean? Any visible corrosion should be removed whether or not it’s currently causing a problem.

Fact is, though, only a voltage drop test can truly answer this question. Place one DMM or scope lead on the battery terminal itself and the other on the bolt or stud at the far end of the same cable. Select Min/Max and DC volts.

Crank the engine with the headlights on high beam, then read the results. If the engine started virtually instantly, you may want to disable fuel or spark, then repeat the test. Ideally, you’ll find a Max reading of .4V or less. Anything higher bespeaks excessive resistance, an undersized cable or excessive starter draw. Known-good values range from the low millivolt (mV) range up to about 400mV, depending on application. Now move to the other battery cable and repeat the sequence. Electronic Specialties’ newly released Starter Buddy, a Motor 2015 Top 20 Tools winner, is designed to perform this test as well. •Are the terminals configured correctly? Many late-model applications feature “intelligent” battery cable ends which incorporate sensors used by the PCM to regulate the charging system output to match measured current flow. Add-on leads at the battery, for a power amp in the trunk, for instance, may provide an unmetered current path that can have serious side effects, including

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hen you find a battery end often allows you to take adterminal that’s loose and vantage of these modular termiwon’t tighten up, you nals and makes for a perfectly acmay want to try using a pair of ceptable repair. Where that’s not what I call “battery unpliers” to re- practical, a much better and more shape it. When possible, align the permanent solution than the temspreadable side of the jaws with porary repair terminal is the crimpthe open slot near the clamping able or solderable cast terminal. A nut. Be sure to loosen the clamping professional-grade kit, with crimping tool, cable cutter and skiving nut fully before reshaping. Parts stores generally carry two knife, allows you to offer customdifferent classes of replacement battery cable end terminals. The temporary repair terminals are cheap and easy to install. In my view, these are designed solely to enable the vehicle to be driven in from your parking lot, and should never become a permanent installation. Left on the vehicle, they inevitably become a breeding ground for corrosion. Many modern vehicles now use modular battery terminals. These are neither difficult nor expensive to replace when necessary. We stock several (both positive and negative) at my shop. Battery “unpliers” are designed to open Swaging on a new ring terminal up and reshape battery cable end termiafter cutting off the original cable nals that no longer tighten properly.

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ers a top-notch repair at a fraction of the cost of cable replacement. Cast terminals, including some specialty terminals for custom applications, are available from many parts suppliers. There are also battery post shims, essentially thimble-shaped adapters specifically designed to take up the space between a worn cable end and the battery post itself. While these are not a favorite of mine, they do provide a reasonably priced solution and may be appropriate for a vehicle that has a limited life expectancy anyway. Proper installation is critical. Use a very thin film of a good silicone-dielectric grease on each surface. Or use a zinc-primer spray coating as an alternative. In either event, be sure to test your installation by giving the cables a good, hard twist. If they move, you still have a problem. No matter what you do, these shims will have a very strong tendency to corrode, so expect that they may need replacement periodically.

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Th the cat

Making Good Connections numerous codes, a discharged battery, a no-start condition, etc. Okay, we’ve got a good battery, the cables are clean and tight, and correctly sized and configured for the vehicle in its original form. What if we want to add on some more goodies? Whether it’s an aftermarket seat heater or a deafening sound system, there’s a right way to do the installation. Once again, there are some basic principles to keep in mind as we go along from here: •The battery’s job is to store enough power to run the lights, starter and ignition. In some cases, it may also have to run certain pieces of auxiliary equipment for a limited period of time, possibly with the engine off—for example, a wheelchair lift. It’s not the battery’s job to run the accessories once the engine is started. At most, the battery will supplement the charging system during high-demand, low-rpm operation. If the anticipated service includes prolonged operation of high-draw electrical accessories with the engine not running, a heavier battery or an additional auxiliary battery may be needed. The simplest test is to run the accessories (with the battery already fully charged) as antici-

Many late-model vehicles incorporate a battery current sensor. In this example, it’s an inductive pickup surrounding the negative battery cable. Some models monitor battery temperature and voltage as well. Adding a ground directly at this battery terminal will cause problems ranging from chronic undercharge to communications errors and even MIL illumination. Best practice calls for grounding a new device to the chassis within 18 in. of its mounting. If you need to run a heavy cable all the way to the front, ground it using the same grounding fasteners as the original chassis ground near the hood hinge.

pated and measure the battery voltage at the conclusion. It should not drop below 9.6V at any time, and should rebound to at least 11.5V within 30 seconds after the loads have been turned off. •If any new accessory will be operated with the key off and will drain the battery substantially on a regular basis, a battery minder or trickle charger may be required to prevent the sulfation that typically accompanies chronic undercharge. Because the discharge occurs during unmonitored operation, this is more likely to be needed in vehicles which carefully match charging rates to current consumption. •Off idle, the generator should be capable of supplying more current than the vehicle actually consumes with all electrical devices turned on. An engineering rule of thumb is that the original equipment alternator/generator output should be twice the designed demand. Experience shows that if the actual demand (with the new accessories in operation) exceeds two-thirds of the generator’s actual maximum output, you should upgrade it. •The B+ terminal of the battery is usually not the right place to connect a new device; this is a prime site for corrosion. Add-on power circuits for devices normally used with the engine running will generally be fed by the generator. That makes it sound like the B+ generator stud would be the perfect site for wiring them in. However, many of today’s vehicles feature a PCM-controlled charging system. In such cases, it’s important that any add-on circuits be on the sensed side of the B+ generator output—that is, downstream of any electrical load-sensing device. Details vary greatly among years, makes and models, so be sure to read the “Description and Operation” section under the Charging System heading in your data and to consult the wiring diagram for each particular vehicle. •If there are several add-on circuits, you may want to use a properly fused single heavy wire to power up an auxiliary fuse panel. Many manufacturers supply one or more B+ studs, often at an underhood power distribution center, main fuse block or underhood relay panel. Use these as needed after conNovember 2015

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Making Good Connections sulting the appropriate wiring diagrams to make sure the new loads are adequately fused and won’t overtax the existing circuitry. If some or all of the new circuits should automatically be off except when the key is in the ON or ACC positions, you may need to wire in one or more relays to accomplish the task,

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circuits if there are no convenient spare cavities in the existing fuse panel.) There are a number of suppliers for auxiliary fuse and relay boxes. Or, if you’re like me, you may have a few known-good relay holders, or even whole fuse boxes that you stripped off various vehicles before scrapping them.

Splicing & Connections

aking proper crimps involves several issues, including size selection, type of connector (such as seamed or seamless) and crimper types. In general, a ratcheting-type crimper offers the greatest reliability and repeatability to assure a consistent result. But it’s important to recognize that most versions of such tools are no respecters of flesh; if you get a patch of palm or finger stuck in there, you’ll have no choice but to see it through, as there is no release until the crimp is complete. Some crimpers use replaceable dies. Make sure your selection is the correct one for the type of connector you’re using. I strongly prefer uninsulated connectors and clear shrink tubing because they allow me to make sure my crimps are properly formed, and allow the next technician to inspect them easily without damaging the insulation in the process. Doubling back the stripped portion going into a splice connector allows you to select the next larger size to allow an extra wire of the original gauge when adding an additional leg at the other end. I prefer to use heat-shrink tubing with a 4:1 shrink ratio and glue inside to seal out moisture and corrosion. It’s possible to miscalculate heat-shrink size and ratio. This can cause the tubing to split, with potentially disastrous results, so make your selection carefully and pay attention when you use your heat gun. Don’t use RTV silicone anywhere wire conductors or connectors are exposed; it releases acetic acid and causes corrosion in the long run. Use either shrink-wrap, a brush-on insulating compound or a good-quality tape. If the area in question is not well-protected in the interior, tape is usually the worst choice. Some amalgamating tapes and special splice-protecting tapes work well enough to withstand most extreme environmental condi-

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but check first for empty cavities in the existing fuse panel. If there’s no better alternative, use the sensed side of the B+ feed on the generator as your power source for the switched leg, then wire in the relay’s switching legs as needed. (You can often piggyback a splice into one of the existing Accessory-switched

tions (snow, ice, rain, baking heat, etc.). But most tapes are simply not designed for long-term exposure to the outside world. The self-fusing amalgamating tape has a soft outer layer and may require additional protection from abrasion with an outer layer of a more traditional vinyl electrical tape. You may have heard of the military splice, a technique used for joining wires without cutting the original conductor. Note these points, though: Because the wire is uncut, you cannot use shrink-wrap tubing to seal out moisture. Soldering the splice will make it more vibration resistant, but also much harder to remove the splice in the future. This may be an important factor if you’re planning a temporary installation, though you can probably just cut off your added wire at a convenient point near the site of any splice. Be sure to terminate it properly to avoid an unintentional short circuit. I strongly prefer a severed and crimped splice, as it’s more easily protected with a quality shrink-wrap tubing. Proper soldering techniques almost deserve an entire article of their own. Fortunately, there are numerous online videos on the subject. The most critical points to remember are: •The wires in the area of the splice must be clean. Don’t use an acidic cleaner; it will just cause more corrosion as time passes. •You must start with a mechanically sound splice. Laying two wires next to one another and covering them with solder won’t provide a lasting, reliable connection. If you can pull the splice apart before it’s soldered, you haven’t made it strong enough. •Heat the joint, not the solder. The joint should be hot enough to make the solder flow. Don’t use an acid-core solder on any electrical circuit. Power splices should be made in the most accessible yet protected location that’s practical. Try to avoid making splices in sections of harnesses subject-

ed to movement or vibration, always anticipating the potential effects of worn engine or transmission mounts, moving pedals and cables, etc. If you need to make a repair splice in an area subject to repeated flexing, like near a door hinge, don’t just pop in a simple butt connector where the wire has broken previously. Instead, cut the old wire at least a few inches away from the flexing area on each side of the break and crimp or solder in a new piece of wire of the same gauge. Fine-stranded wire withstands frequent flexing more readily than thicker strands. The overall gauge should match or exceed the original. Finally, use plenty of small cable ties to properly support wires near the site of a splice to counteract increased brittleness and susceptibility to breakage. As always, use a flush cutter on your cable ties to avoid future injury. Language is not always a precise instrument. I’ve mentioned corrosion as a problem several times in this and other articles, and I’d like to take this opportunity to correct what appears to be a widespread misconception. There is no such thing as corrosion on a wire; there is only corrosion of a wire. When you see that blue or green, remember that it used to be the wire itself. While it’s perfectly acceptable to clean the corrosion off a battery post, terminal or cable end, it’s important to inspect what’s left after the cleaning process to make sure it’s still suitable for use. A solution of baking soda in warm water remains the best bet in most instances. Where a wire has corroded significantly, you can usually repair it by snipping out the damaged section. If this is a small length, you may be able to splice the two ends back together directly, but check to make sure that this will not place undue mechanical strain or tension on the wire, harness retainers or connectors. Otherwise, splice in a sufficient length of wire to restore the harness to a serviceable condition.

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Making Good Connections

Take a careful look at the two huge add-on ring terminals (red wires). How much actual current could either of them supply? Hint: Nowhere near enough, as installed.

Tip: Make a note of the donor vehicle’s VIN so you can easily choose which wires to use based on its wiring. •In general, ground circuit wires should be grounded near to the device, preferably using a wire no more than 18 in. long. Ground wires should be of the same gauge as power feed wires. Unless otherwise specifically required, it’s not

necessary or desirable to run them back to the battery. In fact, doing so may create unwanted ground loop effects such as radio interference or an annoying background hum, or can cause erratic operation of sensitive devices. Additionally, as previously mentioned, some modern electrical systems will not tolerate added ground wires directly at the battery negative terminal. These vehicles typically feature a ground current flow sensor integrated into the ground terminal block assembly or into an inductive pickup encircling the ground cable, as shown in the photo on page 23. If you must add a ground close to the battery, the side of that assembly away from the battery is the appropriate location. Some manufacturers provide a stud, tapped hole or blank cavity for just such needs. There are some things you should avoid doing when dealing with batteries and battery terminals. For example: •Don’t make your new connections

Uni Drive-Shaft Pusher/ Hub Puller # 433 414 Universal tool for pushing out bonded (micro-encapsulated) or heavily corroded drive shafts. Damage to the drive shaft thread is prevented. Suitable for almost all 4- and 5- hole wheel hubs with a pitch circle diameter up to 136mm. The “VIBRO IMPACT” ACT” principle; the vibration impact of the pneumatic wrench is transmitted to the wheel hub and to the drive shaft through the trapezoidal (acme) thread spindle.

Mueller-Kueps LP

5126 South Royal Atlanta Drive Tucker GA 30084 Phone: +1 770 349- 6331 www.mueller-kueps.com [email protected]

*Impact wrench and socket are not included

Ask your local tool truck or distributor

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This wide array of ring sizes and wire gauges merely scratches the surface. If you don’t have in your shop a size that fits, order it up. As you can see, it’s out there.

directly at the battery. •Don’t use sensor ground (DLC pin 5), which flows through the PCM, for that new radio; use chassis ground (DLC pin 4) instead. Tip: Many scan tools jumper pins 4 and 5 internally. If the symptoms disappear with your scanner connected and reappear with it disconnected, suspect a fault affecting one of these two grounds. •Don’t use “vampire” connectors, especially where vibration, moisture or exposure to moisture, salt or ozone is likely. •Don’t cut or tap into either wire of a twisted pair. Twisted-pair cables are used primarily for communications circuits or in sensor data applications such as wheel speed sensor circuits. •Don’t overlook the ground side of any circuit. In some cases, a new, thicker ground cable may be required. •Finally, don’t forget to inspect your work and thoroughly test it under the full gamut of anticipated operating conditions before you ship the vehicle. In much the same way that a starter solenoid works, relays allow us to use small wires and a switch to control a larger current. Because the control wires can be small, we can mount the switch wherever it’s most convenient. We can then mount the relay where it will be as accessible as desired, usually either near our power source or near the new load or, for some antitheft devices, as well-buried as possible. Remember that all power circuits should feature some sort of protection device, be it a fuse or a circuit breaker. Fuses, breakers and other circuit protection devices should be located near the source of the circuit. continued on page 40

Circle #12

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F.Y.I. the tools in advance through a new tool display visible through specific URLs. Another new feature is a vehicle procurement page, which allows the public to be a part of Innova’s product testing. The company will post the vehicles needed so people can search the list and volunteer. Innova has also launched www.coil. innova.com, a website devoted exclusively to its new 4400 Coil and Control Module Tester. This site has a link to the Innova.com website so technicians can directly access the RepairSolutions Web-based service, which assists in quickly and accurately diagnosing and repairing vehicles. Webb Brake Adjusters has created a new website to highlight its complete line of clearance-sensing automatic brake adjusters. The website,

at www.WebbAdjusters.com, offers a part number search function, including competitive numbers, and an online catalog. Other features include a range of resources to assist customers, including fitting instructions and proper slack adjuster maintenance practices, along with aftermarket distribution, product warranty and adjuster identification information. Wells Vehicle Electronics has released 180 new part numbers, expanding its portfolio of OE-quality replacement components for domestic and foreign-nameplate applications to cover an additional 22 million vehicles on the road today. The expansion includes 153 switches, 14 emissions-related parts and 13 sensors. The new numbers are included in the comprehensive online elec-

tronic catalog www.WellsVE.com.

located

at

AP Exhaust Technologies recently announced the acquisition of Eastern Catalytic. The acquisition will combine AP’s full-line exhaust offering and expertise with Eastern’s firstto-market catalytic converter emissions capabilities. For more information, e-mail corpcomm@apexhaust .com.

Missed Something? You can search the archives on the MOTOR website for previously published articles. Visit www.motormagazine.com and click on “Articles.”

Making Good Connections continued from page 26

There’s a maximum safe current capacity for any wire. Too much amperage causes wires to heat up, possibly melting through their insulation and that of other nearby conductors. In the worst case, the wire itself may melt or even ignite. This (minus the igniting part!) is the principle behind fusible links. Every power circuit should incorporate a device to guard against overload. Fuses and inline fuse holders are cheap and readily available, making them the obvious choice for most applications. Select a fuse with an amperage that’s below the current-carrying capacity of the wires it protects but above the anticipated current draw for the device. A good rule of thumb is to choose a fuse no larger than 75% of the rated current-carrying characteristics of the wiring it protects. The wire should already have been selected with a similar safety margin. Duration and duty cycle may also influence wire size selection. High duty cycles or continuous operation loads need heavier wires. Some add-on ac40 40

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cessory devices may incorporate small electric motors or similar components. Like a starter motor, fuel pump or fan, such motors typically draw more current when first activated, then a smaller current once they achieve normal operating conditions. The initial “inrush” current must be accounted for when you make your wiring and fuse selections. Depending on the application, such inrush currents may be five times as high as the normal current consumption once the motor is up to speed. In some instances, typically for relatively high-current applications such as power seat motors, power doors or windows, for example, a self-resetting circuit breaker, known as a type 1, may be the best choice for circuit protection because it requires no replacement or operator intervention when the current draw limits are exceeded. In practice, this often allows the protected circuit to be operated at least for short periods of time even when a partial mechanical or electrical fault causes excessive current draw. Type 1 breakers are often used in accessibility

conversion circuits such as ramps or chair lifts for this reason. In our second case study, the customer’s complaint was that his newly installed mobility scooter lift was running too slowly. A quick look at the power source wiring showed the problem: The installer had used a 10-gauge, ½-in. terminal on a 6mm battery terminal stud to feed the 30A circuit breaker. It was the second terminal of the same size he had installed on that stud. If you look carefully at the photo at the top left corner of page 26, you’ll see that the flanged nut is contacting only a very small fraction of each ring. Moving it to the adjacent 8mm stud and installing an additional larger diameter washer under its nut increased the surface contact area, and the lift speed improved. Of course, a better original choice would have been to use a more appropriately sized ring (and probably a different location) to begin with. This article can be found online at www.motormagazine.com.

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