The Trouble-
shooter’s Toolbox Use this 3-step process to find and eliminate problems in your installation
Troubleshooting is one of the most important tools any technician has available. Unfortunately, By David Parhat
the true skill of troubleshooting is not very well understood by many technicians in the 12-volt indus- try. When faced with a malfunctioning product, it is important to approach the troubleshooting in a systematic manner. Troubleshooting may be considered an art by many, but it is a skill that cannot be learned from reading a book. It can take entire careers to master. Using a routine such as “Identify, Isolate and Eliminate” is very effective and efficient for trouble- shooting. The best installation technicians, such as a Mobile Electronics Certified Professional (MECP), can do more than put a stereo or alarm system in a vehicle. They can diagnose and repair failures quickly. Sometimes an issue is more about how it broke than what is broken. Simply replac- ing product might not solve the actual problem.
THE RIGHT TOOL FOR THE JOB Understanding the troubleshooting process is extremely valuable but before we get too far it’s
important to understand the difference between a digital multi-meter (DMM) and a test light. DMM’s have very high impedance (on the order of mega-ohms) which means they do not affect or alter the circuit they’re attached to. Test lights do not have nearly as high impedance. This means they can change the circuit; specifically, they can load it in ways a DMM won’t. In a worst-case scenario, a test light can destroy transistors or other semiconductors in control modules. Another advantage for the DMM is you can obtain an actual voltage reading, which may ultimately be the problem, whereas with a test light, you cannot tell the voltage by how bright or dim the indicator bulb illuminates. The majority of automotive electrical malfunctions can be traced back to a power or ground connection. Verifying the condition of these connections and all associated fuses is a very good
56 Mobile Electronics June| July 2011
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