GM Service Manual Online
For 1990-2009 cars only

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). Refer to Troubleshooting with a Digital Multimeter in Wiring Systems.
        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 General Electrical Diagnosis in wiring systems for a review of basic electrical troubleshooting.

General Motors Service Training also offers electrical/electronic courses.