174 Auto Electricity and Electronics Copyright by Goodheart-Willcox Co., Inc. Using an Inductive Wire Tracer As discussed in Chapter 6, an inductive wire tracer uses a signal generator and an inductive pickup to fi nd shorts. One is shown in Figure 9-15A. Th e signal generator is con- nected to the vehicle battery, as shown in Figure 9-15B, or to the battery and to the aff ected circuit. Th is produces a weak, fl uctuating voltage in the wiring. Th e pickup, or detector, can then be moved along the outside of the wiring, as shown in Figure 9-15C. It senses the fl uctuating magnetic fi eld around the outside of the wire. If you move the sensor over a short in the wire, the audible tone changes or the tracer makes a beeping sound, depending on the particular tracer. Using a Multimeter As discussed in Chapter 6, a multimeter is a voltmeter, ammeter, and ohmmeter combined in one housing. Also called a VOM (volt-ohm-milliammeter), it is an essential tool for automotive technicians. It can make accurate mea- surements of actual circuit values, which you can compare to known good values. If the test values are high or low, you know a problem exists in the circuit. Multimeters can be analog, digital, or digital-analog. Th e digital-analog meter is the most commonly used in automotive repair. Refer to Chapter 6 for more information about the diff erences in these meters. Figure 9-12. A—A test light is being used to check for power to the power window switch. B—The test light has a sharp, pointed tip. It can be touched on a terminal or pushed through wire insu- lation to touch the conductor. Pierce Insulation to Touch Conductor—Keep Fingers Out of the Way! Touch Probe on Metal Terminal Through Outside of Connector B Connector to Power Window Switch Grounded Test Light A Figure 9-13. To use a self-powered test light, you must first dis- connect the circuit power source. M Battery Switch Motor If Self-Powered Test Light Glows, Path Is Complete Fuse Wire or Component Is Isolated from Power Source Figure 9-14. Using a test light to help find a short circuit. Remember to disconnect the circuit before testing if you are using a self-powered test light. Fuse Block (Fuse Removed) Short to Ground Load Disconnected Load Switch Test Light Glows Until Short Is Found