Engine Controls - Tests W/codes: Other Mazda MPV I

HARD FAILURES

Hard failures cause Malfunction Indicator Light (MIL) 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. See CODE CHARTS. If a sensor fails, control unit 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 Malfunction Indicator Light (MIL) to flicker or illuminate and go out after the intermittent fault goes away. However, the corresponding trouble code will be retained in ECU memory. If related fault does not reoccur within a certain time frame, related trouble code will be erased from ECU memory. Intermittent failures may be caused by a sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES article.

MIL Always ON

1. Verify that engine condition is OK. Retrieve trouble codes. See «RETRIEVING CODES»(ref-18263-S24232341642000123000000) . If code 88 is retrieved, ECU malfunction is indicated. Replace ECU. On federal specification vehicles, if code 00 is retrieved, go to step 2). On California specification vehicles, if code 00 is retrieved, check wiring between ECU terminal 1A and MIL for short to ground.
2. On federal specification vehicles, check if oxygen sensor must be replaced. MIL will come ON every 80,000 miles. To reset the light refer to «MAINTENANCE REMINDER LIGHT RESET PROCEDURES»(ref-162006) . If MIL stays on after following reset procedure, check continuity between MIL and ground. If there is continuity, repair wiring between MIL and ECU. If there is no continuity, check milage sensor for a malfunction. See «INSTRUMENT PANEL»(ref-18264) article.
3. After repairs, clear any codes. See «CLEARING CODES»(ref-18263-S25046475022000123000000) .

MIL Never ON

1. Check if other indicator lamps light during bulb check (ignition ON, engine OFF). If other lamps light, go to step 2). If other lamps do not light, check power supply to instrument panel. See «INSTRUMENT PANEL»(ref-18264) article.
2. Check MIL bulb. If bulb is burnt out, replace. If bulb is not burnt out, ground ECU 1A terminal and check if MIL illuminates. If MIL illuminates, check ECU for malfunction. If MIL does not illuminate, check wiring between ECU and MIL for an open circuit.
3. On federal specification vehicles, check if oxygen sensor must be replaced. MIL will come ON every 80,000 miles. To reset the light refer to «MAINTENANCE REMINDER LIGHT RESET PROCEDURES»(ref-162006) . Check if MIL set screw is loose or missing. Check for mileage sensor malfunction. See «INSTRUMENT PANEL»(ref-18264) article.

CODE CHARTS

Note. See PIN VOLTAGE CHARTS article to identify ECU connector terminals.

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CODE 14: (ATMOSPHERIC PRESSURE SENSOR)

1. Replace engine control unit

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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.