Self-Diagnostic System Check
The SELF-DIAGNOSTIC SYSTEM CHECK is an organized approach for identifying a problem caused by the on-car computer-controlled electronics. Understanding the chart and using it correctly reduces diagnostic time and prevents the unnecessary replacement of parts.
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- A 2-second bulb check of the "SERVICE AIR COND" light at key on (and after engine cranking) confirms battery and ignition voltage to BCM.
- Lighting of "SERVICE NOW/SOON" lights during cranking confirms battery, ignition, and ground integrity to ECM.
- The CCDIC, CCP, and DIC must be functional in order to use the Self-Diagnostics system. Check if panels illuminate and respond when buttons are depressed.
- After entering diagnostics, record all displayed trouble codes and note those displayed during first and second pass. Codes during first pass are intermittents and may require visual inspection of circuitry to isolate. Codes displayed during second pass are hard malfunctions which can be diagnosed using trouble code charts. Perform switch test series to confirm proper operation of these circuits. If any codes fail to pass, refer to appropriate trouble code chart. If no codes are recorded using self-diagnostic test, refer to DFI TESTS W/O CODES article in this section. Malfunctions which are not detected by trouble code or switch test are diagnosed by service of that particular system.