Tomorrow's Technician August 2012 : Page 10
Ground Control Instructor Insight By Carl Fedele The cold season will be upon us sooner than you think and will once again create havoc with automobile electrical systems. There are many types of problems that creep up that can drive even the best of the best technicians crazy. Many times, diagnosing the problem is the hardest part of the electrical repair, not to mention the amount of time involved to get to the proper repair or replace-ment of a certain component. Recently, I have had several calls that involved numerous electrical problems, from fuses constantly blowing, to electrical components that quit working shortly after being replaced, to MILs setting off at the same time. After going through a diagnostic procedure — which begins with the basic voltage check, voltage drops and ground-circuit checks — I’ve found that many of these electrical problems are solved by repairing the ground circuits. This procedure can eliminate wasted time and over-diagnosing on behalf on the technician, not to mention trying to explain the repair to the customer. When confronted with an electrical-related type of call, I usually ask the technician a few basic questions, such as “Is the battery voltage at 12.6V while the engine is off?” I will ask the technician to check the battery voltage while the vehicle is running — which should produce a reading of about 2 volts higher — somewhere around 14.4V to 14.8V. I’ll also have the tech inspect the connec-tions at the battery to make sure they are tight and clean. Next, I recommend looking for any dash warning lights lit, and seeing if are there any diagnostic trouble codes present. Many of today’s automobiles will throw a DTC when experi-encing an electrical problem. But, when dealing with multiple codes, we must start with the first one that appeared and leave the others for later, which could turn out to be false. Many sensors within the automobile share the same ground circuit and power feed. I had one technician call on an electrical problem that involved setting several codes including those involving the crankshaft and camshaft sensor, a mass air flow DTC, along with a random misfire. About the Author Carl Fedele is an automotive instructor at Proviso East High School in Maywood, IL, and Triton College in River Grove, IL. Fedele is an ASE master technician and has a baccalaureate degree in Automotive Technology from Southern Illinois University in Carbondale. 10 TOMORROWSTECHNICIAN.COM 08.12
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