Automotive Computer Codes and Systems

This Haynes manual, shows you how to perform simple diagnostics, as well as how to gain easy access to the on-board computer trouble codes. NOTE: Covers computer controlled cars and light trucks from 1980 through 1999. Features computer trouble codes and troubleshooting information for all major manufacturers. Includes expanded OBD II coverage. The manual includes complete and easy-to-understand code charts for all models, and it is fully illustrated with over 350 b&w photos and drawings.

Book Excerpt

BASIC TROUBLESHOOTING

SYMPTOM-BASED TROUBLESHOOTING NOTE: The problem symptoms and drivability complaints listed in this Section are primarily related to the fuel, emissions and engine management systems. For other possible causes of vehicle problems, refer to the Haynes Automotive Repair Manual for your specific vehicle. This Section provides an easy reference guide to the more common problems that may occur during the operation of your vehicle. Various symptoms and their probable causes are grouped under headings denoting components or systems, such as Engine, Cooling system, etc. Remember that successful troubleshooting isn't a mysterious art practiced only by professional mechanics; it's simply the result of knowledge combined with an intelligent, systematic approach to a problem. Always use a process of elimination starting with the simplest solution and working through to the most complex-and never overlook the obvious. Anyone can run the gas tank dry or leave the lights on overnight, so don't assume that you're exempt from such oversights. Finally, always establish a clear idea why a problem has occurred and take steps to ensure that it doesn't happen again. If the electrical system fails because of poor connection, check all other connections in the system to make sure they don't fail as well. If a particular fuse continues to blow, find out why-don't just go on replacing fuses. Remember, failure of a small component can often be indicative of potential failure or incorrect functioning of a more important component or system. If, and/or when, a check engine light should appear on the instrument panel of your vehicle, don't automatically assume that the faulty component is the computer.

COMPUTER TROUBLE CODE RETRIEVAL

RETRIEVING CODES There are a variety of methods of trouble code retrieval, depending on the manufacturer. Most systems work in conjunction with a light on the dash which illuminates when a fault is detected and a code is stored. The light is marked- "CHECK ENGINE", "POWER LOSS", "SERVICE ENGINE SOON"-or something similar, and is used to blink the codes stores in the computer when manually triggered through the diagnostic connector, if the vehicles computer allows access to trouble codes in this manner. On other models, the code can be accessed by connecting a voltmeter to the diagnostic connector and counting the needle sweeps or in an LED readout on the computer itself. Each manufacturer's procedure for retrieving and clearing trouble codes is described at the beginning of the following tables. Once the codes are retrieved, check them against the chart for your vehicle. Caution: Because engine management systems may differ by year and model, certain trouble codes indicate different problems, depending on the vehicle being repaired. Since this is the case, it would be a good idea to consult your dealer or other qualified repair shop before replacing any electrical component, as they are usually expensive and can't be returned once they are purchased. Some models require a special diagnostic scanner or tool to retrieve the codes. These scanners are easy to use to gather information, and are relatively inexpensive (see Chapter 5).

Subject: Transportation: Automotive: Computer codes, electronic engine management systems manual. ISBN-10: 1563922320 | ISBN-13: 9781563922329 | Haynes 10205