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Which tools are the most efficient to diagnose common vehicle electrical system issues?
ONE OF THE MOST FRUSTRATING THINGS A TECHNICIAN COMES ACROSS when diagnosing a vehicle are intermittent issues. When the issues are on an electrical system, it becomes even more difficult to determine the root cause. We'll cover some common issues technicians face when it comes to working on electrical systems.
Issue 1:
Intermittent shorted or open circuits
Intermittent short circuits usually manifest themselves by blowing a fuse. This can be beneficial, as it gives you a starting point for your diagnosis. Obtaining both the power distribution and wiring diagrams will give you details of components and other possible areas of concern. Additional valuable pieces of information are TSBs and common fixes that have been compiled by repair information sources such as AllData, Mitchell 1 or Identifix.
If there are no known common issues it may be more difficult to locate the root cause of the problem. Some possible sources of intermittent failures are connections with high resistance or loose connecting pins that cause the fuse to heat up and melt. Close inspection of connectors to see if there are signs of overheating such as discoloration of either the pins or the plastic housing is useful. In order to provide a quality repair, it will be necessary to replace the connector pins and the plastic housings on both sides of the connection.
Other causes of intermittent shorts are components themselves. In this case, it may be helpful to measure the resistance within the component using a DMM. Another very effective test is to use an ammeter or other testers, such as the Cal Van Amp Hound 2 or the ESI Fuse Buddy, to measure the current the circuit is actually consuming. If the component is operated with a relay, it will be necessary to activate the relay...