HARD FAILURES
Hard failures cause Malfunction Indicator Light (MIL) to illuminate and remain on until the malfunction is repaired. If light comes on and remains on (light may flash) during vehicle operation, cause of malfunction must be determined using diagnostic trouble code charts. See DIAGNOSTIC TROUBLE CODE CHARTS . If a sensor fails, Powertrain Control Module (PCM) will use a substitute value in its calculations to continue engine operation. In this condition, vehicle is functional, but loss of good driveability will most likely be encountered.
INTERMITTENT FAILURES
Intermittent failures may cause Malfunction Indicator Light (MIL) to flicker or illuminate and go out after the intermittent fault goes away. Corresponding diagnostic trouble code, however, will be retained in Powertrain Control Module (PCM) memory. If related fault does not reoccur within a certain time frame, related diagnostic trouble code will be erased from PCM memory. Intermittent failures may be caused by sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES article.
CLEARING CODES
Use New Generation Star (NGS) Tool (49 T088 0A0) to clear codes. Connect NGS tool to data link connector 2. see scheme 1 Refer to operation manual for proper operation of NGS tool. Select CLEAR function on tool and press trigger. Recheck for diagnostic trouble codes to ensure all codes have been cleared from PCM memory.
DRIVE CYCLE PROCEDURE
Note. Disconnecting battery will reset memory. DO NOT disconnect battery during and after drive cycle procedure. Vehicle speed and engine speed detected by ECM/PCM may differ from that indicated by speedometer and tachometer. Check vehicle speed and engine speed during drive cycle procedure using scan tool. If OBD-II system check is not completed during a drive cycle procedure, OBD-II system detects a malfunction or drive cycle procedure was not completed correctly.
- Connect scan tool. Start engine. Select GENERIC OBDII FUNCTIONS. Select ON BOARD SYSTEM READINESS mode. Check OBDII system check condition. If scan tool displays ALL TESTS ARE COMPLETE, drive cycle procedure does not need to be performed. If scan tool does not display ALL TESTS ARE COMPLETE, go to next step.
- Select PID/DATA MONITOR. Select RFCFLAG and press START. If RFCFLAG status is YES, go to next step. If status is NO, perform DRIVE CYCLE-MODE 1.
- Select ON BOARD SYSTEM READINESS mode. If EVAPORATIVE PURGE SYSTEM check status is YES, go to next step. If check status is NO, perform DRIVE CYCLE-MODE 4.
- Select ON BOARD SYSTEM READINESS mode. If EGR SYSTEM check status is YES, go to next step. If check status is NO, perform DRIVE CYCLE-MODE 2.
- Select ON BOARD SYSTEM READINESS mode. If OXYGEN SENSOR HEATER check status is YES, go to next step. If check status is NO, perform DRIVE CYCLE-MODE 3.
- Select ON BOARD SYSTEM READINESS mode. If OXYGEN SENSOR check status is YES, go to next step. If check status is NO, perform DRIVE CYCLE-MODE 3.
- Select ON BOARD SYSTEM READINESS mode. If CATALYST check status is YES, no further procedure is required. If check status is NO, perform DRIVE CYCLE-MODE 3.
Drive Cycle-Mode 1
Start engine and warm to normal operating temperature. Ensure all electrical and A/C loads are off. Ensure ignition timing and idle speed are within specification. Adjust as necessary. See BASIC TESTING - 1.5L article. Ensure no jumper wires are connected to DLC. Increase engine RPM to specified speed. (Scheme 49) Operate engine at specified RPM for minimum of 15 seconds. Idle engine for more than 20 seconds with cooling fan disabled.
Scheme 49
Drive Cycle-Mode 2
Start engine and warm to normal operating temperature. Ensure all electrical and A/C loads are off. Drive vehicle at specified speed for one minute. (Scheme 50)
Scheme 50
Drive Cycle-Mode 3
Start engine and warm to normal operating temperature. Ensure all electrical and A/C loads are off. Idle engine for additional 5 minutes. Drive vehicle at specified speed (V1) for one minute. Lower vehicle speed to specified speed (V2) for 3 minutes. (Scheme 51)
Scheme 51
Drive Cycle-Mode 4
Ensure following conditions are met
- Engine coolant temperature is 32-95 °F (0-35 °C).
- Intake air temperature is 50-140 °F (10-60 °C).
- Barometric pressure is 72 kPa.
- Fuel gauge needle points within 15-85 percent.
Start and operate engine at 3500 RPM for 200 seconds. Within next 40 seconds, accelerate vehicle to 40-60 MPH (65-96 km/H). Maintain vehicle speed for 6 minutes.
SUMMARY
If no hard fault 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.