• First and foremost, the SAE J1930 regulation dictates that if the PCM controls the alternator field, the alternator is supposed to be dubbed a generator, but if it has its own internal regulator, it’s still OK to call it an alternator.
  • “Limited Slip” and “Positrac” differentials have a set of clutches between the axle gears and the carrier and a heavy S spring between the axle gears to keep spinning to a minimum.
  • Coil output is determined by the mass of the iron core being converted into a magnetic field. Creating this magnetic field takes time, called the current ramp. Once the iron core is saturated, increasing the current flow does not add to that stored m
  • When Cadillac introduced the world's first factory-installed electric headlights in 1912, driving at night was still rare and risky. Steady improvements in power and brightness have reduced the risk, and today's headlights can virtually turn night in
  • Modern scan tools, both OEM and aftermarket, have come a long way. More data parameters to use, faster refresh rates and better graphing all have played a role in making scan tool diagnostics easier. But there are still those occasions when I want to
  • To make power, automotive engines mix air and fuel, then add spark to ignite the mixture in a controlled burn. This burning of the mixture creates pressure and forces the piston down the bore, turning the crankshaft. Because engines are nothing more
  • Even though the optical bus system isn’t being used in extremely high volumes it’s still worth understanding how the system works, what goes wrong, and how to fix it properly.
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  • You may have studied circuits, but you should troubleshoot current paths. Circuits get complicated, and when you troubleshoot current paths, you simplify the complicated.
  • While the basic idea behind the alternator hasn't changed much since it replaced the direct current (DC) generator in the early 1960s, it has evolved to meet new demands. Computer-control is the norm and has impacted charging system diagnostics as te
  • Ignition systems can be one of three basic designs: the distributor ignition system, the distributorless (DIS) ignition system or the coil-on-plug (COP) system. They all perform the same function, but even in the individual systems, design difference
  • Back in November of 2010, Motor Trend magazine named the Chevrolet Volt the "Car of the Year." Making its debut at the same time was the Nissan Leaf, and I believe 2010 will go down in automotive history as the first year mainstream manufacturers off
  • In the early world of automotive ?black box? technology NASA gave us in the 1970s, parallel interface was the only show in town. What that means is that every sensor and actuator had to be hard-wired to the brain box and other than dashboard-mounted
  • Refrigerant leaks are less common than they used to be. Fewer connecting points, lower refrigerant charges and better components are resulting in systems that leak less (as a total annual figure) than older systems used to from the compressor shaft s
  • A wiring schematic is a line diagram of an electrical circuit showing all the components needed to operate the circuit and the wiring paths that connect them. Back in the early days, a diagram including every circuit on the car would only take up a f
  • Want to know a secret? Electronically controlled transmissions on newer vehicles actually are similar to their electronically controlled engines, and often are just as easy to diagnose.
    Figure 1
  • This fine piece of Detroit engineering arrived at the shop on a tow strap, dead in the water. The battery voltage is very low, due to the owner cranking the engine trying to get it started.
  • As the weather warms, more and more of your customers will be switching over their HVAC control settings to Max A/C. And if the system doesn't respond by blowing that refreshing cool air, they will show up at your door to find out why.
  • There was a time that hybrid cars were unusual enough that people would turn their heads and point them out to their friends as one passed by. Those were the days when folks were undecided as to whether this hybrid idea was even going to stick. Of co
  • From the days when automobiles were first built, racing has played an integral role in their development. Racing has been where new technologies are tested and proven on their way to becoming mainstream. It also has been where many ideas are introduc