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 |
|---|---|
| ALDL | Data Link Connector (DLC) |
| Airflow Sensor (AFS) | Mass Airflow (MAF) Sensor |
| Air Temperature Sensor | Intake Air Temperature (IAT) Sensor |
| CHECK ENGINE Light | Malfunction Indicator Light (MIL) |
| 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
HARD FAILURES
Hard failures cause CHECK ENGINE light to illuminate and remain on until problem is repaired. If light comes on and remains on (light may flash) during vehicle operation, cause of malfunction must be determined using diagnostic (code) charts. If a sensor fails, Electronic Control Module (ECM) will use a substitute value in its calculations to continue engine operation. In this condition, commonly known as limp-in mode, the vehicle runs but driveability will not be optimum.
INTERMITTENT FAILURES
Intermittent failures may cause CHECK ENGINE light to flicker or illuminate and go out after the intermittent fault goes away. However, the corresponding trouble code will be retained in Electronic Control Module (ECM) memory. If related fault does not reoccur within a certain time frame, related trouble code will be erased from ECM memory. Intermittent failures may be caused by sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES article.
Federal Models
CHECK ENGINE light will automatically flash at 50,000, 80,000 and 100,000 mile intervals, indicating system inspection and/or system component replacement is required. After necessary services have been performed, turn off CHECK ENGINE light by moving cancel switch to opposite position. Cancel switch is located below steering column lower trim panel.
- At 50,000 Miles - Replace PCV valve and inspect EGR system.
- At 80,000 Miles - Replace O2 sensor.
- At 100,000 Miles - Replace PCV valve, O2 sensor and charcoal canister. Inspect catalytic converter for plugging, EGR system, ECM and related sensors.
Scheme 55
- CHECK ENGINE light will come on when ignition is on and engine is not running. When engine is started, CHECK ENGINE light should go off. If light remains on while engine is running, a trouble code is present.
- If light does not come on with key on and engine off, check CHECK ENGINE light circuit before continuing. See appropriate «INITIAL DIAGNOSTIC PROCEDURE»(ref-25803-S42554192032001010500000) chart under DIAGNOSTIC FLOW CHARTS for each model.
- To retrieve codes, turn ignition off. Install Service Wire in diagnostic terminal, located in engine compartment at firewall. (Scheme 55) Turn ignition on and count flashes of CHECK ENGINE light.
- For example, Code 21 is identified by a flash, flash, pause and flash. After a long pause, Code 21 is repeated twice. (Scheme 56) Each code is displayed 3 times, and then next code is flashed.
- If system is operating properly (with no codes), a Code 12 should exist with ignition on and engine off. This indicates diagnostic system is capable of storing codes.
- Once all codes are displayed, codes will be repeated. Remove fuse from diagnostic terminal in fuse block after stored codes are recorded.
Scheme 56
CLEARING CODES
| CAUTION | Ensure ignition is off when disconnecting or reconnecting power supply for ECM. |
After repairs are performed, clear ECM memory of all stored trouble codes. To clear memory, turn ignition off. Disconnect negative battery cable for at least 20 seconds (Samurai and Sidekick), 30 seconds (Swift DOHC) or 60 seconds (Swift SOHC).
SUMMARY
If no hard fault codes (or only pass codes) are present, driveability symptoms exist or intermittent codes exist, proceed to TESTS W/O CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.