TERMINOLOGY
Due to Federal government requirements, manufacturers may use names and acronyms for systems and components different than those used in previous years. The following table will help eliminate confusion when dealing with these components and systems.
| Former Name Or Acronym | New Name Or Acronym |
|---|---|
| Airflow Sensor (AFS) | Mass Airflow (MAF) Sensor |
| Air Temperature Sensor | Intake Air Temperature (IAT) Sensor |
| CHECK ENGINE Light | Malfunction Indicator Light (MIL) |
| SERVICE ENGINE SOON Light | Malfunction Indicator Light (MIL) |
| Crank Angle Sensor | Camshaft Position (CMP) Sensor |
| Oxygen (O2) Sensor | Heated Oxygen Sensor (HO2S) |
| Pressure Sensor (PS) | Manifold Absolute Pressure (MAP) Sensor |
| Throttle Position Sensor (TPS) | Throttle Position (TP) Sensor |
| Trouble Codes | Diagnostic Trouble Codes DTC(s) |
| Water Temp. Sensor (WTS) | Engine Coolant Temp. (ECT) Sensor |
SAE TERMINOLOGY
FREEZE FRAME DATA
Engine operating conditions can be captured and stored in PCM memory whenever MIL is illuminated. Data captured is called FREEZE FRAME data. Freeze frame data is similar to a single record of operating conditions. Whenever MIL is illuminated, corresponding record of operating conditions is recorded to freeze frame buffer.
Freeze frame data can only be overwritten with data associated with a misfire or fuel trim malfunction. Misfire data takes priority over all other data because of its related part-damaging effects (oxygen sensors, catalytic converters, etc.). Freeze frame data will not be erased unless associated DTC is cleared from PCM memory.
Note. MIL will flash once every second if PCM detects a condition or misfire which could cause damage to catalytic converter.
MALFUNCTION INDICATOR LIGHT (MIL) CHECK
- Turn ignition on. If MIL illuminates, go to next step. If MIL does not illuminate, go to «CIRCUIT TEST A-1»(ref-26219-S30966065042001010500000) for appropriate application. Repair as necessary.
- Start engine. If MIL goes out, system is okay. If driveability problems are present, see «TESTS W/O CODES»(ref-26207) article. If MIL remains on, check for DTCs. See «RETRIEVING DTCS»(ref-26219-S35622957872001010500000) . If no DTC is stored in PCM memory with MIL illuminated, go to «CIRCUIT TEST A-2»(ref-26219-S19966748822001010500000) for appropriate application. Repair as necessary.
RETRIEVING DTCS
DTCs are retrieved using a Tech 1 or other OBD-II compatible scan tool connected to OBD-II 16-pin Data Link Connector (DLC). (Scheme 9) DLC is located below instrument panel, accessible from driver's side. Follow scan tool manufacturer's instructions when retrieving DTCs.
Scheme 9
SUMMARY
If no DTCs are present, and driveability symptoms exist, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
CIRCUIT TESTS
Note. See PIN VOLTAGE CHARTS article and appropriate wiring diagrams in WIRING DIAGRAMS article for PCM connector and wire terminal identification.