Basic Diagnostic Procedure
NOTE:
Subaru Select Monitor (SSM) or an OBD-II generic scan tool must be used to perform basic diagnostic procedure. Follow scan tool manufacturer's instructions for proper operation. Communication with vehicle's on-board computer is through the OBD-II Data Link Connector (DLC). See Fig 1
.
After performing procedures in PRELIMINARY INSPECTION & ADJUSTMENTS, BASIC FUEL SYSTEM CHECKS and BASIC IGNITION SYSTEM CHECKS in BASIC DIAGNOSTIC PROCEDURES article, this is the starting point for utilizing the self-diagnostic system for determining computer-related problems. After performing necessary tests as described in the basic diagnostic procedure, if no codes are indicated and driveability problems still exist, see MALFUNCTION INDICATOR LIGHT DIAGNOSIS in TROUBLE SHOOTING - NO CODES article. Scan tool functions consist of:
- MODE $01
Current powertrain diagnostic data. - MODE $02
Powertrain freeze frame data. - MODE $03
Emission-related powertrain DTCs. - MODE $04
Clear/reset emission-related diagnostic information.
NOTE:
Check for applicable Technical Service Bulletins (TSBs) before proceeding. DO NOT perform the following procedure if driveability conditions are not present. DO NOT turn ignition off during the following procedure or clear DTCs unless instructed to do so.
- 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, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
- Check to see if MIL (CHECK ENGINE) light on instrument cluster illuminates, indicating a system fault. If MIL (CHECK ENGINE) light illuminates, go to next step. If MIL (CHECK ENGINE) light does not illuminate, go to MALFUNCTION INDICATOR LIGHT DIAGNOSIS in TROUBLE SHOOTING - NO CODES article.
- Turn ignition off. Prepare Subaru Select Monitor (SSM) by inserting appropriate diagnostic cartridge and connecting diagnostic cable. Connect SSM or OBD-II generic scan tool to data link connector (DLC). Turn ignition and scan tool on. Retrieve diagnostic trouble codes (DTCs). If any DTCs are stored, save freeze frame data using scan tool MODE $02, then go to next step. If no DTCs are stored, although MIL (CHECK ENGINE) light is illuminated, go to MALFUNCTION INDICATOR LIGHT DIAGNOSIS in TROUBLE SHOOTING - NO CODES article.
- Perform required repair by using procedure associated with DTC retrieved. See SUBARU DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION CHART . If an automatic transaxle DTC is set with other codes, perform basic A/T checks and repair other DTCs first. Basic A/T checks consist of transaxle fluid level, differential fluid level, transaxle fluid leak, differential fluid leak, stall test, line pressure test, transfer clutch pressure test, time lag test, road test and shift characteristics only. See appropriate AUTOMATIC TRANSAXLE OVERHAUL article in AUTOMATIC TRANSMISSIONS.
- After repair, perform clear memory function. See CLEARING DIAGNOSTIC TROUBLE CODES . After clearing DTCs, verify effectiveness of repair. See VERIFICATION PROCEDURE . If repair addresses all issues and no DTCs exist, turn ignition off. Turn scan tool off. Disconnect test mode connector under driver's side of instrument panel. Disconnect scan tool from DLC.