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Infiniti Q45 1992 - 1992 ENGINE PERFORMANCE Self-Diagnostics - Q45
Infiniti Q45 1992 - 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 article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
Infiniti Q45 1992 - SELF-DIAGNOSTIC SYSTEM
Self-diagnostic system is used for diagnosing malfunctions of Electronic Concentrated Control System (ECCS) sensors and actuators. Electronic Control Unit (ECU) has 2 available diagnostic modes. Before entering self-diagnostics, perform BASIC DIAGNOSTIC PROCEDURES. This prevents wasted diagnostic time and invalid diagnostic results.
NOTE: When performing BASIC DIAGNOSTIC PROCEDURES, DO NOT erase any diagnostic information stored in ECU memory.
Infiniti Q45 1992 - HARD FAILURES
Hard failures cause CHECK ENGINE light to glow 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, control unit will use a substitute value in its calculations to continue engine operation. In this condition, commonly known as limp-in mode, vehicle runs but driveability will not be optimum.
Infiniti Q45 1992 - INTERMITTENT FAILURES
Intermittent failures may cause CHECK ENGINE light to flicker or glow and go out after intermittent fault goes away. However, corresponding trouble code will be stored in ECU memory. Not all trouble codes will illuminate CHECK ENGINE light. 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 sensor, connector or wiring related problems. See INTERMITTENTS in TESTS W/O CODES article in the ENGINE PERFORMANCE Section.
NOTE: Follow proper diagnostic routine when diagnosing system. See DIAGNOSTIC ROUTINE table.
Infiniti Q45 1992 DIAGNOSTIC ROUTINE
Procedure Order Basic Diagnostic Procedures 1st Entering Diagnostics 2nd Retrieving Trouble Codes 3rd Symptoms (1) 4th Intermittents (1) 5th
(1) Symptoms and intermittents are covered in TESTS W/O CODES article in the ENGINE PERFORMANCE Section.
Infiniti Q45 1992 - CHECK ENGINE LIGHT
NOTE: Not all trouble codes activate CHECK ENGINE LIGHT.
All models are equipped with a CHECK ENGINE light. As a bulb check, light glows when ignition is turned on and engine is not running.
On California models, CHECK ENGINE light glows when a fault is detected with engine running. A corresponding trouble code will set in ECU memory. CHECK ENGINE light also glows if ECU or crank angle sensor malfunctions.
On Federal models, CHECK ENGINE light glows only when ECU or crank angle sensor malfunctions with engine running.
Infiniti Q45 1992 - DIAGNOSTIC MODES
Self-diagnostic system can detect ECCS malfunctions and store related trouble codes. Intermittent codes are also stored. All codes are stored until cleared from memory. If an intermittent does not reoccur within 50 ignition key cycles, it will be cleared from memory.
Switching modes is not possible when engine is running. During diagnosis, self-diagnostic system will automatically return to Mode I from Mode II when ignition is turned off.
Infiniti Q45 1992 - Mode I
This is normal operating mode. In this mode, CHECK ENGINE light and Red Light Emitting Diode (LED) inspection light in ECU stay on when ignition is turned on, engine off (bulb check). If engine is started, CHECK ENGINE light and Red LED in ECU should turn off, unless a fault or trouble code is present (California) or if ECU or crank angle sensor is malfunctioning (California and Federal).
Infiniti Q45 1992 - Mode II
This is self-diagnostic mode for retrieving fault or trouble codes. See RETRIEVING CODES. With engine running, Mode II can monitor air/fuel mixture feedback control. CHECK ENGINE light and red LED in ECU will flash on (lean) and off (rich) more than 5 times every 10 seconds with engine speed at 2000 RPM when system is in closed loop. CHECK ENGINE light and red LED do not flash (remain on or off) if system is in open loop.
Infiniti Q45 1992 - ECU LOCATION
ECU is located behind right kick panel.
Infiniti Q45 1992 - ENTERING SELF-DIAGNOSTICS
- Turn ignition on, but leave engine off. Using a small screwdriver, turn diagnostic mode selector on ECU fully clockwise. Wait at least 2 seconds, and then turn diagnostic mode selector fully counterclockwise. Mode II self-diagnostics will result and CHECK ENGINE light and Red LED inspection light will flash codes (if present).
- If engine is started at this stage, CHECK ENGINE light and Red LED inspection light will display condition of air/fuel mixture, monitored by O2 sensor, whether system is in closed or open loop.
NOTE: Turn back diagnostic mode selector to fully counterclockwise position whenever vehicle is in use. Switching modes is not possible when engine is running.
Infiniti Q45 1992 - RETRIEVING CODES
Use Mode II to retrieve trouble codes from self-diagnostic system. Read codes using either CHECK ENGINE light or Red LED inspection light on ECU. Trouble codes will flash after selecting Mode II.
Trouble codes are indicated by number of flashes from CHECK ENGINE light or Red LED inspection light. For example, 3 long (.6 second) flashes followed by 2 short (.3 second) flashes of CHECK ENGINE light or Red LED indicate a Code 32.
Infiniti Q45 1992 - CLEARING CODES
NOTE: Ensure all diagnostic codes are accessed from ECU memory before disconnecting battery or switching from Mode II to Mode I.
Infiniti Q45 1992 - Memory Erase
Stored memory can be erased by disconnecting battery or selecting Mode I after Mode II has been accessed.
Infiniti Q45 1992 - DIAGNOSTIC TROUBLE CODE DEFINITION
NOTE: When using trouble code charts, refer to Fig. 1 for symbol identification.
Infiniti Q45 1992 DIAGNOSTIC TROUBLE CODE IDENTIFICATION CHART
Code System Affected Probable Cause 11 (1) Crank Angle Sensor (2) No Crank Signal 12 Airflow Meter Circuit Open/Shorted Circuit 13 Coolant Temperature Sensor Open/Shorted Circuit 14 Vehicle Speed Sensor (VSS) No VSS Signal 16 Traction Control System (3) No TCS Signal 21 (1) Ignition Signal Circuit (2) Open/Shorted Circuit 31 ECU Signals Not Normal 32 (4) EGR Function No EGR Action 33 O2 Sensor (Left) Open Circuit/High O2 Signal 34 (1) Knock Sensor Open/Shorted Circuit 35 (4) Exhaust Temperature Sensor Open/Shorted Circuit 43 Throttle Sensor Open/Shorted Circuit 45 (4) Injector Leak Leak At Injectors 46 (4) (W/TCS) Secondary Throttle Position Sensor Open/Shorted Circuit 51 (4) Injector Circuit Injector Does Not Work 53 O2 Sensor (Right) Open Circuit/High O2 Signal 54 (1) Automatic Transmission Signal Open Signal Transmission Control Unit 55 (1) No Malfunction (Q45) Normal Condition
(1) Trouble code will not activate CHECK ENGINE light.
(2) If Codes 11 and 21 are present at same time, check items causing a malfunction of crank angle sensor circuit first.
(3) See ANTI-LOCK BRAKE SYSTEM article in the BRAKES Section.
(4) California models.
Fig. 1: Infiniti Q45 1992 - Component Locations - Identifying Trouble Code Chart Symbols
Infiniti Q45 1992 - TROUBLE CODE CHARTS
NOTE: Most code charts shown include procedures using Nissan Consult Tester (J-38465). If consult tester is not available, disregard steps using consult tester and use alternate test procedure. OK = Okay; NG = No Good.
Infiniti Q45 1992 - DTC 11 - CRANK ANGLE SENSOR
Fig. 2: Infiniti Q45 1992 - Component Locations - Code 11 Schematic - Crank Angle Sensor
Fig. 3: Infiniti Q45 1992 - Component Locations - Code 11 Connector Location - Crank Angle Sensor
Fig. 4: Infiniti Q45 1992 - Component Locations - Code 11 Flow Chart - Crank Angle Sensor
Infiniti Q45 1992 - DTC 12 - AIRFLOW METER
Fig. 5: Infiniti Q45 1992 - Component Locations - Code 12 Schematic - Airflow Meter
Fig. 6: Infiniti Q45 1992 - Component Locations - Code 12 Connector Location - Airflow Meter
Fig. 7: Infiniti Q45 1992 - Component Locations - Code 12 Flow Chart - Airflow Meter
Infiniti Q45 1992 - DTC 13 - ENGINE (COOLANT) TEMPERATURE SENSOR
Infiniti Q45 1992 - DTC 14 - VEHICLE SPEED SENSOR
Fig. 11: Infiniti Q45 1992 - Component Locations - Code 14 Schematic - Vehicle Speed Sensor
Fig. 12: Infiniti Q45 1992 - Component Locations - Code 14 Connector Location - Vehicle Speed Sensor
Fig. 13: Infiniti Q45 1992 - Component Locations - Code 14 Flow Chart - Vehicle Speed Sensor
Infiniti Q45 1992 - DTC 16 - TRACTION CONTROL SYSTEM (TCS) SIGNAL
Fig. 15: Infiniti Q45 1992 - Component Locations - Code 16 - Flow Chart - TCS System Signal
Infiniti Q45 1992 - DTC 21 - IGNITION SIGNAL CIRCUIT
Fig. 17: Infiniti Q45 1992 - Component Locations - Code 21 Schematic - Ignition Signal Circuit
Fig. 20: Infiniti Q45 1992 - Component Locations - Code 21 Flow Chart - Ignition Signal Circuit
Infiniti Q45 1992 - DTC 31 - ENGINE CONTROL UNIT (ECU)
Fig. 21: Infiniti Q45 1992 - Component Locations - Code 31 Flow Chart - Engine Control Unit (ECU)
Infiniti Q45 1992 - DTC 32 - EGR SYSTEM FUNCTION
Fig. 22: Infiniti Q45 1992 - Component Locations - Code 32 Schematic - EGR System Function
Fig. 23: Infiniti Q45 1992 - Component Locations - Code 32 Connector Location - EGR System Function
Fig. 24: Infiniti Q45 1992 - Component Locations - Code 32 Flow Chart (1 of 2) - EGR System Function
Fig. 25: Infiniti Q45 1992 - Component Locations - Code 32 Flow Chart (2 of 2) - EGR System Function
Infiniti Q45 1992 - DTCS 33 & 53 - LEFT & RIGHT OXYGEN SENSORS
Infiniti Q45 1992 - DTC 34 - KNOCK (DETONATION) SENSOR
Fig. 29: Infiniti Q45 1992 - Component Locations - Code 34 Schematic - Knock (Detonation) Sensor
Fig. 31: Infiniti Q45 1992 - Component Locations - Code 34 Flow Chart - Knock (Detonation) Sensor
Infiniti Q45 1992 - DTC 35 - EXHAUST GAS TEMPERATURE SENSOR
Infiniti Q45 1992 - DTC 43 - THROTTLE POSITION SENSOR
Fig. 33: Infiniti Q45 1992 - Component Locations - Code 43 Schematic - Throttle Position Sensor
Fig. 35: Infiniti Q45 1992 - Component Locations - Code 43 Flow Chart - Throttle Position Sensor
Infiniti Q45 1992 - DTC 45 - INJECTOR LEAK
Fig. 36: Infiniti Q45 1992 - Component Locations - Code 45 Flow Chart - Injector Leak
Infiniti Q45 1992 - DTC 46 - SECONDARY THROTTLE SENSOR
Fig. 37: Infiniti Q45 1992 - Component Locations - Code 46 Schematic - Secondary Throttle Sensor
Infiniti Q45 1992 - DTC 51 - INJECTOR CIRCUIT
Fig. 41: Infiniti Q45 1992 - Component Locations - Code 51 Schematic - Injector Circuit
Fig. 42: Infiniti Q45 1992 - Component Locations - Code 51 Connector Location - Injector Circuit
Fig. 43: Infiniti Q45 1992 - Component Locations - Code 51 Flow Chart (1 of 3) - Injector Circuit
Fig. 44: Infiniti Q45 1992 - Component Locations - Code 51 Flow Chart (2 of 3) - Injector Circuit
Fig. 45: Infiniti Q45 1992 - Component Locations - Code 51 Flow Chart (3 of 3) - Injector Circuit
Infiniti Q45 1992 - DTC 54 - AUTOMATIC TRANSMISSION SIGNAL
Fig. 46: Infiniti Q45 1992 - Component Locations - Code 54 Schematic - Automatic Transmission Signal
Infiniti Q45 1992 - 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.