Ohmmeter

Electrical troubleshooting requires the use of common electrical test equipment.

The ohmmeter function on a DMM can be used instead of a self-powered test light. An ohmmeter shows how much resistance there is between two points along a circuit. Low resistance means good continuity.

Circuits which include any solid state control modules, such as the PCM, should be tested only with a 10-megohm or higher impedance J 39200 digital multimeter.

Before measuring resistance with a DMM, disconnect the vehicle's battery. This will prevent incorrect readings. DMMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading.

Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement.