Using Available Diagnostic Information

1. Following a Flow of Diagnosis will usually lead to the correct test procedure and help repair the problem.

2. The On-Board Diagnostic Circuit Check should ALWAYS be performed whether or not a computer related problem is suspected. The check may reveal computer problems which were not originally suspected. Bypassing this test during diagnosis may lead to replacement of good parts. Refer to "Computers And Control Systems/System Diagnosis/Procedures/On-Board Diagnostic System Check." Testing and Inspection

3. If you can't readily locate a test procedure to help diagnosis the problem, additional component and system information can be found in these areas:

^ Diagnostic Charts - may contain useful system descriptions, circuit description, wiring diagrams or diagnostic notes. Look here to see if the system you are working on has a related system test.

- A-Charts (System Testing) - may contain useful system descriptions, circuit description, wiring diagrams or diagnostic notes. Look here to see if the system you are working on has a related system test. You may perform these tests even if you have not been directed (unless otherwise noted). Refer to "Computers And Control Systems/System Diagnosis/Procedures/Diagnostic Charts/A-Charts." Testing and Inspection

- C-Charts (Sub-System and Component Testing) - may contain useful component descriptions, circuit description, wiring diagrams or diagnostic notes. Look here to see if the component you are working on has a specific component test. You may perform these tests even if you have not been directed (unless otherwise noted). Refer to "Computers And Control Systems/System Diagnosis/Procedures/Diagnostic Charts/C-Charts". Testing and Inspection

- Diagnostic Trouble Code Charts - may be reviewed for diagnostic notes and circuit descriptions. Refer to "Computers And Control Systems/System Diagnosis/Procedures/Diagnostic Charts/Diagnostic Trouble Code Charts". Engine Control System

CAUTION: Trouble Code charts should Never be used to diagnose a component unless that trouble code has been stored. Using the trouble code chart without a stored trouble code may lead to incorrect diagnosis and replacement of good parts.

^ Diagnosis by Symptom - should be used when a driveability problem is present, symptoms don't point to a particular system or component, and no diagnostic trouble codes are stored. Refer to "Diagnosis By Symptom" under "System Diagnosis/Procedures" under the appropriate major sub-system title.

^ System or Component Descriptions - Sometimes getting a better idea of HOW a system or component works can help with diagnosis of a problem. Refer to the "Description and Operation" for the specific system or component in question.

NOTE: Specific diagnostic charts or test procedures available for a particular vehicle may not be available for others (depending on system applications.)