General Diagnostic Information

To use this manual most effectively, a general understanding of basic electrical circuits and circuit testing tools is required. One should be familiar with wiring diagrams, the meaning of voltage, ohms, amps, the basic theory of electricity, and understand what happens in an open or shorted wire.
To perform system diagnosis, the use of a diagnostic Scan tool is required. A tachometer, test light, digital ohmmeter with 10 megohms impedance, vacuum gauge, and jumper wires are also required. Please become acquainted with the tools and their use before attempting to diagnose a vehicle.

DIAGNOSTIC INFORMATION
The diagnostic trouble tree charts and functional checks in this manual are designed to locate a faulty circuit or component through logic based on the process of elimination. The charts are prepared with the requirement that the vehicle functioned correctly at the time of assembly and that there are no multiple failures. Trouble tree charts are designed to be used only when a diagnostic trouble code is active.
The Powertrain Control Module (PCM) performs self-diagnostics of powertrain control functions. The PCM communicates faults with a system of Diagnostic Trouble Codes (DTCs). These DTCs may or may not turn on the Malfunction Indicator Lamp (MIL) (SERVICE ENGINE SOON) or SERVICE lamp to alert the driver.