For 1990-2009 cars

A basic knowledge of the following items is required for use of this section:

(Use of the diagnostic procedures in this section will be difficult without this basic knowledge.)

#### Basic Electrical Circuits

An understanding of the following concepts is required:

• | The basic theory of electricity

• | The meaning of the following terms:

- | Voltage

- | Current (amperes)

- | Resistance (ohms)

• | The result of an open or shorted wire in a circuit

• | How to read and understand a wiring diagram

#### Use Of Circuit Testing Tools

An understanding of the following concepts is required:

• | The use of the J 39200 Digital Multimeter (DMM)

| Knowledge of the controls and their correct use is required.

| Important: Use a solid, unpainted chassis ground or the negative battery cable when measuring the resistance to ground.

• | How to measure the value of the following items:

- | Voltage

- | Resistance

- | Current

• | The correct use of jumper wires for the following purposes:

- | Bypassing components

- | Testing circuits

Refer to How to Use Electrical Diagnosis in Wiring Systems for a review of basic electrical troubleshooting knowledge.

General Motors Service Training also offers electrical/electronic courses.