Engine Controls Diagnostic System Check: Testing
- Check for one or more of the following conditions:
- Malfunction Indicator Light (MIL) illuminates during engine operation.
- Customer concern of powertrain performance or driveability problem.
- A suspected malfunction in a powertrain controlled component or system.
- Turn ignition off. Turn ignition on, with engine off. Connect a scan tool to Data Link Connector (DLC). Turn scan tool power on. If scan tool displays DTCs, go to next step. If scan tool does not display any DTCs, go to TEST C: SCAN TOOL DOES NOT COMMUNICATE WITH KEYWORD DATA LINE under SYSTEM TESTS.
- Attempt to start engine. If engine cranks, go to next step. If engine does not crank, check engine electrical. See ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM.
- If engine cranks, starts and idles, go to next step. If engine cranks, but does not start, repair as necessary. See appropriate TROUBLE SHOOTING - NO CODES article in ENGINE PERFORMANCE.
- Check for Technical Service Bulletins (TSB) that addresses concern. Perform TSB repair as necessary. If TSB repair corrected condition, system is okay at this time. If TSB repair did not correct condition, go to next step.
- Engine Control Module (ECM) DTCs, P0601, P0602, P0603, P0604, or P0606.
- System voltage DTCs.
- Component level DTCs: sensors, solenoids, relays etc. Multiple DTCs within this category should be diagnosed in numerical order starting with lowest numbered DTC.
- System level DTCs: misfire, fuel trim, etc.
- Transmission DTCs. See POWERTRAIN ON BOARD DIAGNOSTIC (OBD) SYSTEM CHECK - AUTOMATIC TRANSMISSION DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM.
- Using scan tool, check for DTCs. If any DTCs displayed, go to next step. If no DTCs are displayed, go to step 8 .
- Using scan tool, capture FREEZE FRAME information. Also, note any non-emissions related DTCs that are set, but are not in FREEZE FRAME buffer. Perform appropriate test in accordance with DTC retrieved. See DIAGNOSTIC TROUBLE CODE DEFINITIONS .
- Ensure scan tool data values are normal values or within typical ranges. See appropriate TROUBLE SHOOTING - NO CODES article in ENGINE PERFORMANCE.
NOTE:
If multiple DTCs are stored, priority of diagnosis is:
NOTE:
Capturing stored FREEZE FRAME information will preserve data that is lost when DTCs are cleared at completion of diagnostic procedure or if an ECM disconnect occurs during a diagnostic procedure. FREEZE FRAME data is stored in scan tool memory. Any non-emissions DTCs that are set should be written down at this time. FREEZE FRAME only stores data for emissions related DTCs. Captured information should be reviewed at end of diagnostic table in order to catch next DTC in event that multiple DTCs were stored. Follow diagnosis order priority as previously listed.