186 Auto Electricity and Electronics Copyright by Goodheart-Willcox Co., Inc. Figure 9-38. You must use common sense and the basic rules given in this chapter when making electrical measurements. By think- ing about the circuit and specific components, you should be able to use logical steps to find circuit problems. Signal Processor Ohmmeter Ohmmeter Disconnect Wires to Check Continuity Typical Sensor (Input Information) Checking for Good Ground ECM Ground Ohmmeter Voltage Drop Electronic Control Module Typical Solenoid (Controlled Function) Voltmeter Disconnected Component Check Supply Voltage R Battery Voltage Voltmeter – +