- How to Use This Section

1. Following a Flow of Diagnosis will usually lead to the correct test procedure and help repair the problem.
2. The Diagnostic Circuit Check (under Computers and Control Systems/Testing Procedures) should ALWAYS be performed whether or not a computer related problem is suspected. The "Diagnostic Circuit Check" may reveal computer problems which were not originally suspected. Bypassing this test during diagnosis may lead to replacement of good parts. Testing and Inspection
3. If test procedures cannot fix the problem (or is not available), you can find additional component and system information in these areas:
^ System 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. You may perform these tests even if you have not been directed (unless otherwise noted). Refer to System Diagnostic Charts found under Computers and Control Systems, Testing And Inspection/Procedures. Testing and Inspection
^ C-Charts (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 C-Charts found under Computers and Control Systems, Testing And Inspection/Procedures. Testing and Inspection
^ Diagnostic Trouble Code (DTC) Charts - may be reviewed for diagnostic notes and circuit descriptions. Refer to Diagnostic Trouble Code (DTC) Charts found under Computers and Control Systems, Testing And Inspection/Procedures. Testing and Inspection

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 Symptoms - should be used when no computer related problems appear. Refer to the related system (Computers and Control Systems, Fuel Control Systems, Ignition Control System, etc.)
^ System or Component Descriptions - Sometimes getting a better idea of HOW the system or component works can help with diagnosis of a problem.

NOTE: Charts or Tests mentioned may not be available for the specific vehicle you are working on.