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 and also verifies 12.0 volts out of the CPS to the IPC.

2. The CRT must be functional in order to use the self diagnostic system. Check the screen for illumination and response when the pads are touched.

3. Refer to HOW TO ENTER DIAGNOSTIC MODE. After entering diagnostics, record all displayed trouble codes and note those that display "Current" versus "History".

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.