Chapter 22 POWERPOINT

Use the textbook to define these Technical Terms:

1. electrical diagnosis

2. infinite resistance

3. intermittent problem

4. jumper wire

5. open circuit

6. short circuit

7. voltage drop measurement

8. zero resistance

Use the textbook to answer these discussion questions:

1. Explain 2 causes of basic circuit problems given their symptoms.

Read the chapter summary below:

Summary

■ Most circuit problems are caused by something very simple, such as a broken wire or loose terminal connection. However, when this basic trouble is in a complex circuit, it can be very difficult to locate and repair. Correct techniques must be used to find electrical problems in a modern vehicle.

■ Use a systematic approach to diagnose electrical trouble. First verify a problem and analyze the symptoms. Then narrow down the possible causes of the problem. Perform the proper tests to find the exact trouble. After making the repair, recheck to be sure the problem has been corrected before releasing the vehicle to the customer.

■ If only one component does not work, start your tests at that component. If several components in the same circuit are not working, start your tests at the power source to the circuit.

■ Common circuit problems include an open circuit, high circuit resistance, short circuit, and intermittent circuit problems.

■ Jumper wires, test lights, inductive circuit tracers, and multimeters are important testing devices and can be used to find most types of circuit trouble.

■ A voltmeter must be connected in parallel with the circuit. A conventional ammeter must be connected in series with the circuit. An inductive ammeter has a lead that clips over the outside of the wire. An ohmmeter must not be connected to a source of power. It uses internal batteries to measure circuit or component resistance.

■ Voltage drop measurements provide an easy way of checking for high resistance. You do not have to disconnect the power source and isolate the component, as with an ohmmeter. A high voltage drop indicates a high resistance. A low voltage drop indicates a low resistance.

■ Learning how to perform basic tests on connectors, resistors, switches, fuses, and other basic components will help you understand how to test more complex components.