Infiniti M30 1992 - 1992 ENGINE PERFORMANCE Self-Diagnostics - M30

Infiniti M30 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 M30 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 M30 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 M30 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 M30 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 M30 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 M30 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 M30 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 M30 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 M30 1992 - ECU LOCATION

ECU is located behind right kick panel.

Infiniti M30 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 M30 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 M30 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 M30 1992 - Memory Erase

Stored memory can be erased by disconnecting battery or selecting Mode I after Mode II has been accessed.

Infiniti M30 1992 - DIAGNOSTIC TROUBLE CODE IDENTIFICATION

NOTE:

When using trouble code charts, refer to Fig. 1 for symbol identification.

Infiniti M30 1992 DIAGNOSTIC TROUBLE CODE IDENTIFICATION CHART

Code

System Affected

Probable Cause

11 ⁽¹⁾

Crank Angle Sensor

⁽²⁾ No Crank Signal

Airflow Meter Circuit

Open/Shorted Circuit

Coolant Temperature Sensor

Open/Shorted Circuit

Vehicle Speed Sensor (VSS)

No VSS Signal

21 ⁽¹⁾

Ignition Signal Circuit

⁽²⁾ Open/Shorted Circuit

22 ⁽¹⁾

Fuel Pump Circuit

Open/Shorted Circuit

ECU

Signals Not Normal

32 ⁽³⁾

EGR Function

No EGR Action

O2 Sensor (Left)

Open Circuit/High O2 Signal

34 ⁽¹⁾

Knock Sensor

Open/Shorted Circuit

35 ⁽³⁾

Exhaust Temperature Sensor

Open/Shorted Circuit

Fuel Temperature Sensor

Open/Shorted Circuit

Throttle Sensor

Open/Shorted Circuit

45 ⁽³⁾

Injector Leak

Leak At Injectors

51 ⁽³⁾

Injector Circuit

Injector Does Not Work

⁽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⁾	California models.

Fig. 1: Infiniti M30 1992 - Component Locations - Identifying Trouble Code Chart Symbols

Infiniti M30 1992 - DIAGNOSTIC TROUBLE CODE CHARTS READ THIS FIRST

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.