Handbook 652 Body Electrical Diagnosis Measuring Resistance Resistance tests are primarily used for determining: • Circuit continuity to locate opens, shorts, or grounds. • Component resistance to determine if it meets specifications. When using an ohmmeter, disconnect the component from the circuit to isolate the measurement from other current flow paths and voltage sources. Voltage drop tests are quicker and more reliable for diagnosis because high resistance can be missed by resistance testing. Sometimes high resistance can only be found when attempting to operate the load. CAUTION Applying voltage to the test leads when the meter is set to measure resistance can damage some meters.
Always disconnect power before measuring resistance. 30 Technical Training