Diagnostic Circuit Check

Self-Diagnostic System Check:

DESCRIPTION:

This check is an organized approach for identifying a problem caused by the on-car computer controlled electronics. Understanding this chart and using it correctly will reduce diagnosis time, prevent the unnecessary replacement of parts, and reduce comebacks.

TEST DESCRIPTION: Numbers below refer to the circled numbers on the diagnostic chart.

1. "SERVICE ENGINE SOON" telltale at key-on confirms battery, ignition, and ground integrity to the ECM/PCM and also verifies ignition 1 feed to the IPC.

2. The IPC odometer is the primary display device for diagnostics and must be functional in order to use the Self-Diagnostic system.

3. The ECCP serves as the access for on-board diagnosis and must be functional in order to use the Self-Diagnostic System. A display other than the standard temperature indicates a fault that must be corrected before diagnostics can be entered.

4. After entering diagnostics, record all displayed trouble codes and note those that display current versus history. Codes displayed can be diagnosed using the procedures under DIAGNOSTIC CHARTS, however, those codes displayed as history are not presently failing and may require a visual inspection of circuitry to isolate.

5. Failure of the S.E.S. light to go out in the expected time period indicates an ECM/PCM problem.

NOTE: The charts under DIAGNOSTIC CHARTS are driveability and component testing charts. The computer communication/display diagnostic charts are in TESTING PROCEDURES under SELF-DIAGNOSTIC SYSTEM.