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Engine Controls - Tests W/codes Mazda 929 HD

Testing & Diagnostics 25 illustrations ~496 words

INTRODUCTION

If no faults were found while performing BASIC TESTING , proceed with self-diagnostics. If no fault codes or only pass codes are present after entering self-diagnostics, proceed to TESTS W/O CODES article in the ENGINE PERFORMANCE section for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).

HARD FAILURES

Hard failures cause CHECK ENGINE 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 (code) charts. If a sensor fails, control unit will use a substitute value in its calculations to continue engine operation. In this condition, vehicle is functional, but driveability may be poor.

INTERMITTENT FAILURES

Intermittent failures may cause CHECK ENGINE light to flicker or illuminate and go out after the intermittent fault goes away. The corresponding trouble code, however, will be retained in control unit memory. If related fault does not reoccur within a certain time frame, related trouble code will be erased from control unit memory. Intermittent failures may be caused by sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES article in the ENGINE PERFORMANCE section.

Accessing Trouble Code

  1. Connect jumper wire between diagnostic connector terminals TEN and GND. (Scheme 4) Diagnostic connector is located at left front wheelwell.
  2. With ignition on and engine stopped, observe CHECK ENGINE light or Malfunction Indicator Light (MIL). Note trouble codes. See TROUBLE CODE IDENTIFICATION chart for possible cause. If light remains on continuously, MIL circuit is grounded or ECU is defective.

AFTER-REPAIR PROCEDURE

After indicated service or replacement is performed, clear codes. See CLEARING CODES. Recheck ECU memory. No codes should be present. If codes are present, see appropriate trouble code chart to repair vehicle.

Scheme 4

Scheme 4: AFTER-REPAIR PROCEDURE
Scheme 4: AFTER-REPAIR PROCEDURE

Clearing Trouble Codes

  1. Disconnect negative battery cable. Depress brake pedal for at least 5 seconds. Reconnect battery cable.
  2. Ground test connector with jumper wire. Turn ignition on, but do not start engine for 6 seconds. Operate engine at 2000 RPM for 2 minutes. Verify no codes are displayed.

Scheme 5

Scheme 5: TROUBLE CODE IDENTIFICATION
Scheme 5: TROUBLE CODE IDENTIFICATION

Scheme 6

Scheme 6
Scheme 6

TROUBLE CODE IDENTIFICATION TABLE

DTCDescription
CODE 2Crankshaft Position Sensor - NE2 Signal
CODE 3Distributor G Signal
CODE 4Distributor NE1 Signal
CODE 5Left Knock Sensor
CODE 6Vehicle Speed Sensor
CODE 7Right Knock Sensor
CODE 8Airflow Meter
CODE 9Coolant Thermosensor
CODE 10IAT - Airflow Meter
CODE 11IAT - Dynamic Chamber
CODE 12Throttle Sensor
CODE 14Atmospheric Pressure
CODE 15Left Side Oxygen Sensor
CODE 16EGR Position Sensor
CODE 17Left Side Feedback System
CODE 23Right Side Oxygen Sensor
CODE 24Right Side Feedback System
CODE 26Purge Control Solenoid Valve
CODE 28EGR Vacuum Solenoid Valve
CODE 29EGR Vent Solenoid Valve
CODE 30Cold Start Injector Relay
CODE 34Idle Speed Control
CODE 36Right/Left O2 Sensor Heater Relay
CODE 37Right/Left O2 Sensor Heater Relay
CODE 41Variable Resonance Induction System
CODE 65A/C Input Signal

TROUBLE CODE IDENTIFICATION

TROUBLE CODE CHARTS

Note. See PIN VOLTAGE CHARTS article in the ENGINE PERFORMANCE section to identify ECU connector terminals.

Scheme 7

Scheme 7: CODE 2: (CRANKSHAFT POSITION SENSOR - NE2 SIGNAL)
Scheme 7: CODE 2: (CRANKSHAFT POSITION SENSOR - NE2 SIGNAL)

Scheme 8

Scheme 8: CODE 3: (DISTRIBUTOR G SIGNAL)
Scheme 8: CODE 3: (DISTRIBUTOR G SIGNAL)

Scheme 9

Scheme 9: CODE 4: (DISTRIBUTOR NE1 SIGNAL)
Scheme 9: CODE 4: (DISTRIBUTOR NE1 SIGNAL)

Scheme 10

Scheme 10: CODE 5 & 7: (LEFT/RIGHT KNOCK SENSOR)
Scheme 10: CODE 5 & 7: (LEFT/RIGHT KNOCK SENSOR)

Scheme 11

Scheme 11: CODE 6: (VEHICLE SPEED SENSOR)
Scheme 11: CODE 6: (VEHICLE SPEED SENSOR)

Scheme 12

Scheme 12: CODE 8: (AIRFLOW METER)
Scheme 12: CODE 8: (AIRFLOW METER)

Scheme 13

Scheme 13: CODE 9: (COOLANT THERMOSENSOR)
Scheme 13: CODE 9: (COOLANT THERMOSENSOR)

Scheme 14

Scheme 14: CODE 10: (IAT - AIRFLOW METER)
Scheme 14: CODE 10: (IAT - AIRFLOW METER)

Scheme 15

Scheme 15: CODE 11: (IAT - DYNAMIC CHAMBER)
Scheme 15: CODE 11: (IAT - DYNAMIC CHAMBER)

Scheme 16

Scheme 16: CODE 12: (THROTTLE SENSOR)
Scheme 16: CODE 12: (THROTTLE SENSOR)

CODE 14: (ATMOSPHERIC PRESSURE)

If code No. 14 is present, replace ECU.

Scheme 17

Scheme 17: CODE 15 & 23: (LEFT/RIGHT SIDE OXYGEN SENSOR)
Scheme 17: CODE 15 & 23: (LEFT/RIGHT SIDE OXYGEN SENSOR)

Scheme 18

Scheme 18: CODE 16: (EGR POSITION SENSOR)
Scheme 18: CODE 16: (EGR POSITION SENSOR)

Scheme 19

Scheme 19: CODE 17 & 24: (LEFT/RIGHT SIDE FEEDBACK SYSTEM)
Scheme 19: CODE 17 & 24: (LEFT/RIGHT SIDE FEEDBACK SYSTEM)

Scheme 20

Scheme 20
Scheme 20

Scheme 21

Scheme 21: CODE 26: (PURGE CONTROL SOLENOID VALVE)
Scheme 21: CODE 26: (PURGE CONTROL SOLENOID VALVE)

Scheme 22

Scheme 22: CODE 28: (EGR VACUUM SOLENOID VALVE)
Scheme 22: CODE 28: (EGR VACUUM SOLENOID VALVE)

Scheme 23

Scheme 23: CODE 29: (EGR VENT SOLENOID VALVE)
Scheme 23: CODE 29: (EGR VENT SOLENOID VALVE)

Scheme 24

Scheme 24: CODE 30: (COLD START INJECTOR RELAY)
Scheme 24: CODE 30: (COLD START INJECTOR RELAY)

Scheme 25

Scheme 25: CODE 34: (IDLE SPEED CONTROL)
Scheme 25: CODE 34: (IDLE SPEED CONTROL)

Scheme 26

Scheme 26: CODE 36 & 37: (RIGHT/LEFT O2 SENSOR HEATER RELAY)
Scheme 26: CODE 36 & 37: (RIGHT/LEFT O2 SENSOR HEATER RELAY)

Scheme 27

Scheme 27: CODE 41: (VARIABLE RESONANCE INDUCTION SYSTEM)
Scheme 27: CODE 41: (VARIABLE RESONANCE INDUCTION SYSTEM)

Scheme 28

Scheme 28: CODE 65: (A/C INPUT SIGNAL)
Scheme 28: CODE 65: (A/C INPUT SIGNAL)

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 in the ENGINE PERFORMANCE section for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.

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