This DIY manual by Haynes, shows you how to troubleshoot your vehicle's fuel injection system using common tools and on-board diagnostics computer. In addition, the manual also covers step-by-step checks and component replacement. Topics covered by this manual include:

• Electronic fuel injection systems (foreign and domestic)
• All system types including CIS, CIS-E, and Motronic systems
• Fuel pressure testing
• Throttle body repair and overhaul
• Computer codes
• The latest fuel injection tools

Book Excerpt: Haynes Fuel Injection Manual 1986-1999 Domestic and Imported Models COMPUTER TROUBLE CODES

GENERAL INFORMATION When diagnosing problems on engines controlled by computer systems, remember that many drivability symptoms and/or problems may not necessarily be caused by the computer. The computer is only responding to the input (or change of input information) of the many sensors controlled by the fundamental systems previously discussed in this Book. Unless all of the basic engine systems are properly functioning, the electronic controls have inaccurate information to manage the engine fuel and emissions systems properly. Condemning a computer, input sensor or output actuator, before verifying that the fundamental systems are operating correctly usually leads to an incorrect diagnosis. Besides wasting your time, you'll find that the electronic components of engine management systems are generally expensive and usually not returnable, even if a mistake has been made in diagnosis. Before proceeding to the electronic control system tests make the following general checks:

1. The engine is in good overall mechanical condition, as indicated by compression and vacuum tests.
2. The battery is clean and free of connection corrosion, in good condition and fully charged.
3. The starting and charging systems operate properly.
4. All fuses and fusible links are intact.
5. All electrical connectors are free of corrosion and connected securely.
6. All vacuum lines are in good condition, correctly routed, and attached securely.
7. The air and fuel supply systems are free of restrictions and working properly.
8. The PCV, EGR, and EVAP and other emissions systems are working properly and maintained as required.
9. The coolant level and condition is good, and the thermostat is in place and is of the correct operating temperature.
10. The engine oil level and condition are good.
11. The ignition system is in good condition with no signs of cross-firing, mis-firing, carbon tracks, corrosion, or wear.
12. The base timing and idle speed are set to specifications found on the VECI label.
13. The computer is going into closed loop operation.

Note: If in doubt about the condition of any of these items, refer to the appropriate Sections of Chapter 8 and recheck the component(s) or systems in question. On-board computer systems not only control the engine fuel, ignition and emission functions in an attempt to achieve optimum efficiency, but on most systems they also have a built-in diagnostic feature. When the computer detects a fault, it stores a trouble code in its memory. The code can usually be retrieved from the computer's memory by following a certain procedure. A trouble code doesn't necessarily indicate the exact cause of a problem, but it will direct you to a particular component, circuit or system, which may simplify diagnosis.

Subject: Transportation: Automotive: Fuel Systems: Fuel Injection: 1986-1999 domestic and imported vehicle fuel injection system repair manual. 1986, 1987, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999. ISBN-10: 1563923866 | ISBN-13: 9781563923869 | Haynes 10220