What do you really need to know about starting, charging and ignition systems? Two things, basically. Electrical and ignition problems are often difficult to diagnose and replacing parts until a problem goes away creates a lot of unnecessary (and expensive) returns and warranty issues. That’s why many stores have a "no return" policy on electrical components. Once the part has been installed on a customer’s vehicle, he owns it. If the part turns out to be defective, it can still be exchanged for a free replacement. But if the customer is throwing parts at a problem and the newly installed part fails to fix it, he can’t bring it back for a refund.
What’s your role in all of this? Traditionally, the counterman’s function has been part salesman and part order picker. Your customer tells you what part he wants to replace and gives you the year, make and model of his vehicle. You then look up the correct replacement part, pick it off the shelf (or order it from the warehouse if it is out of stock) and sell it to your customer.
You may also compare the old and new parts to make sure they appear to be the same. If your store has a battery tester and/or starter/alternator test bench, you may also offer to test the customer’s original part to make sure it is defective. This is a great way to avoid unnecessary returns and warranty issues, but it does require the know-how to operate the test equipment.
Depending on the customer and the situation, you may also be asked for repair or installation advice. This requires a certain amount of system knowledge. You need to know what the basic parts are in the starting, charging and ignition systems, what these parts do, why they sometimes fail and any related items that should also be inspected or replaced (like cleaning, inspecting and replacing, if necessary, the battery cables when a new battery is installed).
In situations where there are various brands or types of parts to choose from, you may also have to provide additional information about the differences, benefits or cost advantages of Brand A versus Brand B; reman versus new or "economy" versus "standard" versus "premium" (good, better, best). This requires an in-depth knowledge of the products you sell as well as a higher level of salesmanship.
Some parts stores are also asking their counter people to diagnose customer’s vehicles, too. When a customer comes in with a "Check Engine" light on, you may be asked to plug a scan tool into his vehicle to read out a diagnostic trouble code. The code will tell you something about the nature of the problem and, hopefully, which system or component may be involved. One thing to keep in mind about codes is they don’t actually tell which part needs to be replaced. The code only shows a fault has been detected in a particular circuit or component, which means further diagnosis is almost always necessary to isolate and identify the fault.
A misfire code, for example, may tell you which cylinder is misfiring but not what’s causing the misfire. It might be a fouled spark plug or a bad plug wire. But, it might also be a weak ignition coil, a dirty or dead fuel injector, or a compression leak caused by a burned or bent valve, or a blown head gasket.
Nobody said your job was easy. And it’s only going to get harder as automotive technology becomes more and more complex. So let’s quickly review the basic components in the starting, charging and ignition systems so you can better understand and sell these parts.
The battery is a voltage reservoir that provides electricity to crank the engine, and to operate the ignition system, onboard electronics and other electrical accessories. All automotive batteries are 12 volts (12.6 volts when fully charged). Inside are six cells with lead plates surrounded by an electrolyte, a very corrosive mixture of water and sulfuric acid. In "gel" batteries, the acid is held in a paste between the plates, so it cannot leak or spill. The chemical interaction between the acid and lead plates is what produces and stores the electricity.
Automotive batteries must be kept at or near full charge to function properly. If the battery becomes discharged (run down), it may not be able to provide enough current to start the engine or operate the other electronic or electrical systems on the vehicle. If the battery is left in a discharged state for very long (more than a few days), it can suffer permanent damage that will reduce its ability to accept a charge and produce current. Batteries can run down if there is a problem with the charging system, or if the vehicle is not driven often enough or long enough to fully recharge the battery.
Average battery life is only about four or five years. Hot weather shortens battery life by increasing evaporation of the liquid inside. Cold weather slows the chemical reactions and reduces the battery’s ability to produce power. If a battery won’t hold a charge, goes dead and won’t accept a charge or tests defective, it must be replaced.
Batteries come in different "group" sizes that vary according to their dimensions and post configuration. A replacement battery must be the same or a compatible group size.
Batteries also have different power ratings. One of these is Cold Cranking Amps (CCA). Bigger is usually better. A replacement battery should have the same or higher CCA rating as the original battery (typically 450 to 600 CCAs). The bigger the engine, the more amps it needs for reliable cold weather starting.
When batteries are sold, sell the oldest ones first to keep your stock fresh. The date code reveals when the battery was manufactured. The number indicates the year, and the letter corresponds to the month (A = January, B = February, C = March, etc.).
Customers will also have to decide how much "warranty" they want to buy. Replacement batteries come with warranties that typically range from 24 to 72 months. As a rule, the longer the warranty, the better the battery – and the higher the price.
Batteries should be fully charged before they are installed. The vehicle’s charging system should also be checked to make sure it is operating correctly. The charging voltage should usually be about 1-1/2 to 2 volts higher than battery voltage.
Other items that may be needed include battery cables, anti-corrosion washers for the battery terminals, a new battery tray and/or battery hold-down hardware and clamps.
The starter motor cranks the engine when the engine is started. There are several basic types: direct drive, gear reduction and permanent magnet. Starter motors usually last for many years because they are only used for starting.
The most common cause of starter failure is prolonged cranking. This causes the motor to overheat. Starters also wear out after years of service if the brushes, bushings or starter drive become worn. Starters also have a solenoid that routes current to the motor when the ignition switch is turned to the crank position. A defective solenoid will prevent the starter from working. The starter drive mechanism that engages the flywheel may also stick or fail preventing the starter from working. Most times, the solenoid and drive mechanism can be replaced separately.
A replacement starter (new or reman) must have the same bolt pattern and electrical connections as the original, and the same number of teeth on the drive gear. Exchange units must be the correct one for the application and complete to receive full core credit. Permanent magnet starters must be handled with care because the magnets are brittle and can easily crack. Related items that may also have to be replaced include battery cables and engine ground straps.
The alternator is a belt-driven generator that produces electricity to keep the battery charged, and to provide amperage for the ignition system, fuel injectors, fuel pump, lights and electrical accessories. Alternators produce alternating current (AC), which is converted to direct current (DC) by a diode trio (rectifier) on the back of the unit.
Alternator charging output increases in proportion to the electrical load on the charging system and engine speed. Charging output is controlled by a "voltage regulator" which may be mounted inside or on the back of the alternator "internally regulated," or somewhere else under the hood "externally regulated." On most newer vehicles, the powertrain control module (PCM) regulates charging output.
If an alternator is overloaded, it may overheat and fail. An alternator failure will cause the battery to run down and go dead. Symptoms of a charging problem include a low battery, dim head lights, hard starting or a charging system warning light.
A replacement alternator (new or reman) should have the same or higher amp rating as the original. If the replacement comes with a pulley (some do not), make sure it matches the original (same diameter, width and belt type).
Related items that may also need to be replaced include the regulator (externally regulated applications only), drive belt, battery cables and/or battery.
All gasoline engines use spark plugs to ignite the air/fuel mixture. Most engines have one spark plug per cylinder, but a few have two. Each spark plug has electrodes on the end which a spark jumps across when high voltage is routed to the plug from the ignition coil.
Spark plugs eventually wear out and can become fouled by carbon deposits. A fouled plug may misfire causing a loss of power and fuel economy, and a big increase in exhaust emissions. Fouled or worn spark plugs can make an engine hard to start and run poorly. Replacing the spark plugs can restore normal performance.
Under normal driving conditions, a set of standard spark plugs will usually last about 45,000 miles.
Refer to the vehicle owners manual for the recommended replacement interval. Long life plugs, which have center electrodes made of wear-resistant metals such as platinum or iridium, typically go up to 100,000 miles before replacement is needed. Plugs with platinum on both the center and ground electrodes ("double" platinum plugs) or those with multiple ground electrodes experience even less wear than plugs with a single platinum or platinum-tipped electrode. When selling replacement spark plugs, upgrading to a long life platinum or iridium plug can extend service intervals. For more information on long-life plugs, see Platinum & Beyond.
Spark plugs have different thread sizes (metric and SAE), different diameters, lengths, electrode configurations and "heat" ranges. Replacement plugs must be physically interchangeable with the original plugs and have similar heat characteristics. Follow the plug manufacturer’s recommendations or refer to the vehicle owner’s manual or emissions decal.
SPARK PLUG WIRES
The spark plug wires (ignition cables) carry high voltage from the coil or distributor to the spark plug. Some wires have carbon-impregnated fiberglass strands inside to carry the voltage while others have spiral-wound "mag" wire. There is one plug wire for each spark plug, and the wires can be replaced individually or in sets.
Plug wires can deteriorate with age causing misfires, hard starting and poor performance. Wires should be replaced if the boots or terminals are loose, damaged or corroded, if the wires are cracked or sparking or if their internal resistance exceeds specifications.
On late model engines with coil-on-plug (COP) ignition systems, there are no plug wires because the coils are mounted directly on the spark plugs. On engines with coil-near-plug (CNP) ignition systems, each individual coil has a short plug wire that connects to the spark plug. The wire is part of the coil assembly and cannot be replaced separately.
Wire sets come in various types: economy, standard, premium and performance. The higher the grade (and the price) of the wire set, the more durable are the materials used in the wires and insulation. As a rule, the whole set of wires should be replaced if one or more of the old wires are in poor condition. Wires should be installed one at a time so as not to mix up their firing order.
The ignition coil is a transformer that provides high voltage to fire the spark plugs (25,000 to 40,000 volts!). If the engine has a distributor, it will have one coil for the entire ignition system. If the engine has a distributorless ignition systems (DIS), there may be one coil per cylinder, or one coil for every pair of cylinders.
Coils seldom fail, but when they do they can’t provide voltage to the spark plug(s). On a single coil ignition system, a coil failure will cause the engine to quit and prevent it from starting. On a multi-coil ignition system, it will cause a misfire in only one or two cylinders (if the coil is shared).
Coils can be tested by measuring their internal resistance with an ohm meter. If the coil’s "primary" or "secondary" resistance is out of specifications, the coil needs to be replaced. Performance upgrade coils provide more voltage for reliable ignition at higher engine speeds.
Electronic ignition systems all use some type of transistorized switching module to turn the coil(s) on and off. On some vehicles (GM and Ford), the module may be mounted on or in the distributor. On DIS systems, it is often part of the coil pack assembly. Modules can be damaged by heat and vibration. A module failure will usually cause a no-spark, no-start condition. GM High Energy Ignition (HEI) modules in older vehicles require a thin layer of dielectric grease underneath to conduct heat away from the module. Forget the grease and the module may not live long.
Ignition modules may receive a trigger signal directly from a distributor pickup (magnetic, Hall effect or Optical), a crankshaft position (CKP) sensor or the PCM. A fault in any of these other components or the wiring can prevent the ignition system from firing.