Engine Controls - Self-Diagnostics - Introduction: Other Mazda MX-5 NB

SERVICE PRECAUTIONS

Before proceeding with diagnosis, following precautions must be observed

1. Ensure vehicle has a fully charged battery and function charging system.
2. Visually inspect connectors and circuit wiring being worked on.
3. Do not cause short circuits when performing electrical tests. This will set additional DTCs, making diagnosis of original problem more difficult.
4. Do not use a test light in place of a voltmeter.
5. When a vehicle has multiple DTCs, always repair lowest number DTC first.

MALFUNCTION INDICATOR LIGHT (MIL)

If DTCs are present, MIL is illuminated when malfunction is detected after 2 consecutive drive cycles. One exception is if a misfire malfunction is detected that may damage catalytic converter, the MIL will illuminate or flash immediately and DTC will be set. If malfunction is no longer present, MIL will go off between 3 to 4 drive cycles. DTC will be erased from memory after 41 engine warm-ups.

RETRIEVING CODES

Connect scan tool to data link connector. (Scheme 28) Start engine. Select DIAGNOSTIC TEST MODE and press trigger. If NO CODES RECEIVED/SYSTEM PASSED is displayed, all monitored systems are okay. If DTCs are present, see DIAGNOSTIC TROUBLE CODE IDENTIFICATION. See applicable DIAGNOSTIC TEST in appropriate SELF-DIAGNOSTICS article. If LINK MONITOR ERROR is displayed, check scan tool connection. Once all repairs have been completed, go to CLEARING CODES (POST-REPAIR PROCEDURE).

Scheme 28

CLEARING CODES (POST-REPAIR PROCEDURE)

Note. DTCs may also be cleared by disconnecting battery, but learned values for mass airflow sensor and throttle position sensor will be erased.

Once repairs are completed, connect scan tool to DLC. Select CLEAR function and erase DTCs from memory. Perform drive cycle procedure twice. See appropriate drive cycle. See DRIVE CYCLE PROCEDURE . Start engine and retrieve DTCs. If DTCs are present, see applicable DTC test in appropriate SELF-DIAGNOSTICS article. If no DTCs are present, repair is complete.

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 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.

1. Connect scan tool. Start engine. Select GENERIC OBD-II FUNCTIONS. Select ON BOARD SYSTEM READINESS mode. Check OBD-II 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.
2. 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»(ref-91095-S05837441472001030200000) .
3. 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»(ref-91095-S14756964392001030200000) .
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»(ref-91095-S05914833342001030200000) .
5. 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»(ref-91095-S31979834452001030200000) .
6. 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»(ref-91095-S31979834452001030200000) .
7. 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»(ref-91095-S31979834452001030200000) .

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 DIAGNOSTIC PROCEDURES article. Ensure no jumper wires are connected to DLC. Increase engine RPM to specified speed. (Scheme 29) Operate engine at specified RPM for minimum of 15 seconds. Idle engine for more than 20 seconds with cooling fan disabled.

Scheme 29

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 30)

Scheme 30

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 31)

Scheme 31

Drive Cycle-Mode 4

Ensure following conditions are met

1. Engine coolant temperature is 32-95 °F (0-35 °C).
2. Intake air temperature is 50-140 °F (10-60 °C).
3. Barometric pressure is 72 kPa.
4. 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. (Scheme 32)

Scheme 32

FREEZE-FRAME DATA

This mode allows access to emission related data values from specific generic PIDs. These values are immediately stored in continuous memory when an emission related fault occurs. This provides a snapshot of the conditions that were present when the fault occurred. Freeze frame will be stored until PCM memory is erased.

SUMMARY

If no diagnostic trouble code is present but driveability problem still exists, proceed to TROUBLE SHOOTING - NO CODES article for symptom diagnosis or intermittent diagnostic procedures.