The fuel injection or carburetor system, described in detail in Fuel System of this guide, is operated along with the ignition system to obtain optimum performance and fuel economy while producing a minimum of exhaust emissions. The various sensors described in this section are used by the computer control module (ECM, PCM or VCM-A depending upon application) for feedback to determine proper engine operating conditions.
Although most diagnosis may be conducted using a Digital Volt/Ohm Meter (DVOM), certain steps or procedures may require use of the TECH 1® diagnostic scan tool (a specialized tester) or an equivalent scan/testing tool. If the proper tester is not available, the vehicle should be taken to a reputable service station which has the appropriate equipment.
When dealing with the electronic engine control system, keep in mind that the system is sensitive to improperly connected electrical and vacuum circuits. The condition and connection of all hoses and wires should always be the first step when attempting to diagnose a driveability problem. Worn or deteriorated hoses and damaged or corroded wires may well make a good component appear faulty.
When troubleshooting the system, always check the electrical and vacuum connectors which may cause the problem before testing or replacing a component.
For more information on troubleshooting the electronic engine control system, please refer to the information on self-diagnostics later in this section.