The multimeter combines multiple electrical diagnosis functions into one portable unit. One of the more frequently used functions of the multimeter is the ohmmeter.
The ohmmeter measures resistance in Ohms (Ω). In the above video, Purkeys National Truck & Fleet Representative, Larry Rambeaux, demonstrates how to test resistance on a 5-pin relay using an ohmmeter.
One thing commonly tested on heavy-duty trucks is the 5-pin relay. Many technicians are quick to replace this part without properly testing it first. To test it, technicians need to know what the resistance should be according to manufacturer specifications. Technicians will also need to know how to use Ohm’s Law (V=I*R) to see if everything is working within specifications.
Service manuals are written with the presumption that technicians know how to properly use an ohmmeter and understand its readings. If they do not understand the manual, the readings, or the ramifications of the readings, they can spend a lot of time misdiagnosing the actual issue.
The ability of a technician to properly use and understand an ohmmeter can do wonders for a fleet. That is why Purkeys offers a wide range of training on how to properly use every function of multimeters, including ohmmeters.
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