Testing Procedure

Diagnosis of computerized engine control system should be performed in the following order:

1. Ensure all engine systems not related to computer system are operating properly. DO NOT proceed with testing unless all other problems have been repaired. Use Customer Complaint Check List in BASIC DIAGNOSTIC PROCEDURES article and verify customer complaint and conditions under which fault appears. Attempt to start engine. If engine starts, go to next step. If engine does not start, perform no-start diagnosis. See NO-START DIAGNOSIS in BASIC DIAGNOSTIC PROCEDURES article.
2. Check illumination of CHECK ENGINE light (MIL). See MALFUNCTION INDICATOR LIGHT (MIL) INSPECTION . If CHECK ENGINE light illuminates, go to next step. If CHECK ENGINE light does not illuminate, see MALFUNCTION INDICATOR LIGHT DIAGNOSIS .
3. Retrieve diagnostic trouble codes (DTCs). See RETRIEVING DIAGNOSTIC TROUBLE CODES . If DTCs are present, go to next step. If DTCs are not present, check MIL circuit. See MALFUNCTION INDICATOR LIGHT DIAGNOSIS . If MIL circuit is okay and no DTCs are present but a driveability problem exists, go to TROUBLE SHOOTING - NO CODES article.
4. Perform diagnosis and repair for stored DTC. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . After necessary repairs are made, clear DTCs, and perform verification of repair to ensure DTC does not reset. See CLEARING DIAGNOSTIC TROUBLE CODES  and VERIFICATION PROCEDURE  .
5. If automatic transaxle DTCs are displayed, perform the following basic checks. Afterward, repair or replace components as required.
   • Check ATF fluid level.
   • Check differential gear oil level.
   • Check for ATF fluid leaks.
   • Check for differential gear oil leaks.
   • Perform stall test.
   • Perform line pressure test.
   • Perform transfer clutch pressure test.
   • Perform time lag test.
   • Perform road test.
   • Check shift characteristics.
   After necessary repairs are made, clear DTCs, and perform verification of repair to ensure DTC does not reset.