Engine Controls - Tests W/codes Nissan Sentra B13

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.).

ELECTRONIC CONCENTRATED CONTROL SYSTEM (ECCS)

Self-diagnostic system is used for diagnosing malfunctions of Electronic Concentrated Control System (ECCS) sensors and actuators. Electronic Control Unit (ECU) has a number of available diagnostic modes within computer.

All models have 2 modes with subdivisions. Before selecting any mode of self-diagnosis, always perform procedures listed in BASIC TESTING article in the ENGINE PERFORMANCE Section. Doing so prevents wasted time and invalid diagnostic results.

Consult Tester

In addition to self-diagnostic capability, NX and Sentra models are equipped with a diagnostic connector for use with Nissan's Consult Tester (J-38465 ). Connector is located behind fuse box cover.

Note. When performing BASIC TESTING , be careful not to erase any diagnostic information stored in ECU memory.

Hard Failures

Hard failures cause CHECK ENGINE light (if equipped) 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. If a sensor fails, ECU will use a substitute value in its calculations to continue engine operation. In this condition (fail-safe mode), the vehicle runs but driveability will not be optimum and engine speed is restricted (2000-3000 RPM depending on model).

Intermittent Failures

Intermittent failures may cause CHECK ENGINE light (if equipped) to flicker or illuminate and go out after intermittent fault goes away. However, corresponding trouble code will be retained in ECU memory. If related fault does not reoccur within 50 ignition cycles, related trouble code will be erased from ECU memory. Intermittent failures may be caused by sensor, connector or wiring problems. See INTERMITTENTS in TESTS W/O CODES article in the ENGINE PERFORMANCE Section.

Note. Follow diagnostic routine when testing ECCS. See DIAGNOSTIC ROUTINE table for correct order of procedure.

DIAGNOSTIC ROUTINE

CHECK ENGINE LIGHT

All models are equipped with a CHECK ENGINE light. As a bulb check, light will illuminate when ignition is on and engine is not running. CHECK ENGINE light will also illuminate when an ECCS fault has been detected. Not all trouble codes activate CHECK ENGINE light.

DIAGNOSTIC MODES

Self-diagnostic system can detect ECCS malfunctions and store related trouble codes. Trouble codes, including intermittent codes, are stored in ECU memory and are available for interpretation unless codes have been cleared.

Self-diagnostic system uses single Light Emitting Diode (LED), located on ECU.

SINGLE LED SYSTEM

Self-diagnostic system will operate in 2 modes which are manually selected using a screwdriver through access port on ECU. With ignition switch in ON position and engine not running, use screwdriver to turn switch fully clockwise. Wait at least 2 seconds. Turn screwdriver fully counterclockwise. Inspection light will begin to flash.

Note. Modes cannot be switched while engine is running. When ignition switch is turned to OFF position while in Mode II, ECU switches to Mode I.

Mode I (Bulb Check)

Engine is not running in this mode. Turn ignition switch to ON position. Red LED on ECU and CHECK ENGINE light (if equipped) should be lit. If light(s) do not illuminate, check and replace bulbs as necessary.

Mode I (Malfunction Warning)

This is normal vehicle operating mode and engine must be running. On California vehicles, if a malfunction occurs, red LED and CHECK ENGINE light (if equipped) will illuminate, indicating an ECCS malfunction has occurred and a code has been stored. On Federal vehicles, codes are stored and only red LED will illuminate when ECU's Central Processing Unit (CPU) malfunctions.

Mode II (Self-Diagnostics)

When Mode II is accessed (engine not running), codes stored in ECU memory will be flashed by CHECK ENGINE light (if equipped) and red LED on side of ECU.

A long flash (.6 second) indicates first digit of code. Short flashes (.3 second) indicates second digit of code. For example: 1 long flash followed by 2 short flashes indicate a Code 12. (Scheme 48)

Scheme 48

Mode II (Exhaust Gas Monitor)

In Mode II (engine running), both red LED and CHECK ENGINE light are used to monitor air/fuel mixture feedback control. Vehicle must be in closed loop for Mode II results to be valid.

In open loop, red LED remains either on or off. In closed loop, red LED indicates if system is running rich (light off), lean (light on) or at ideal air/fuel ratio (blinking synchronized with CHECK ENGINE light).

If 2 oxygen sensors are used (left and right side), left side is monitored first. To switch to right side: With engine running, turn screwdriver fully clockwise. Wait at least 2 seconds. Turn screwdriver fully counterclockwise. Inspection light will begin to flash. This is Mode II.

ENTERING SELF-DIAGNOSTICS

1. Self-diagnostic system normal operational mode is Mode I. With ignition switch in ON position and engine not running, insert screwdriver through access port on ECU.
2. Turn screwdriver fully clockwise. Wait at least 2 seconds. Turn screwdriver fully counterclockwise. Inspection light will begin to flash. This is Mode II.

Note. Modes cannot be switched when engine is running. When ignition switch is turned to OFF position, ECU will switch to Mode I.

RETRIEVING CODES

When Mode II is accessed (engine NOT running), codes stored in ECU memory will be flashed by CHECK ENGINE light and red LED on side of ECU. A long flash (.6 second) indicates first digit of code. Short flashes (.3 second) indicate second digit of code. For example: 3 long flashes followed by 5 flashes of red LED (or CHECK ENGINE light) indicate a Code 35.

TROUBLE CODE DEFINITION

Note. Not all trouble codes will activate CHECK ENGINE light.

TROUBLE CODE IDENTIFICATION CHART (1.6L)

TROUBLE CODE IDENTIFICATION CHART (2.0L)

CLEARING CODES

Note. Ensure all diagnostic codes are extracted from ECU memory before disconnecting battery or manually erasing stored memory.

Memory Erase

Stored memory will be erased if battery is disconnected for 24 hours or diagnostic mode is switched from Mode II to Mode I (modes cannot be switched with engine running). To switch from Mode II to Mode I while in Mode II with engine off, turn diagnostic mode selector fully clockwise. Wait for at least 2 seconds, and turn mode selector fully counterclockwise.

ECU LOCATION

ECU LOCATION

CODE CHARTS INTRODUCTION

Note. When CODE CHART step indicates CHECK COMPONENT, see indicated component in I - SYS/COMP TESTS article in the ENGINE PERFORMANCE Section. For trouble code chart symbol identification (Scheme 49) To identify ECU connector terminals, see WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section.

FINAL STEPS FOR ALL CODE CHARTS

Unless otherwise instructed in code chart, perform following steps after repair

1. Reinstall any part removed.
2. Erase self-diagnostic memory. See CLEARING CODES under «SELF-DIAGNOSTIC SYSTEM»(/nissan/sentra/b13-1990-1994/remont/testing-diagnostics/#engine-controls-tests-wcodes) .
3. Ensure Code 55 (no malfunction) is displayed in self-diagnostic mode.
4. Test drive vehicle.
5. Perform self-diagnostics.

If code resets, check for damage to ECU pin terminals and connector harness.

Scheme 49

CODE CHARTS (1.6L)

Note. Some code charts include procedures using Nissan's Consult Tester (J-38465 ). If consult tester is not available, disregard steps using consult tester and use alternate test procedure. The following abbreviations appear on charts: OK=Okay; NG=No Good.

Scheme 50

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Scheme 54

Scheme 55

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Scheme 59

EXHAUST GAS SENSOR VOLTAGE (NG DATA) (1.6L)

EXHAUST GAS SENSOR VOLTAGE (OK DATA) (1.6L)

EXHAUST GAS SENSOR VOLTAGE (OK DATA) (1.6L)

Scheme 60

Scheme 61

Scheme 62

CODE CHARTS (2.0L)

Note. Some code charts include procedures using Nissan's Consult Tester (J-38465 ). If consult tester is not available, disregard steps using consult tester and use alternate test procedure. The following abbreviations appear on charts: OK=Okay; NG=No Good.

Scheme 63

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Scheme 71

EXHAUST GAS SENSOR VOLTAGE (NG DATA) (2.0L)

EXHAUST GAS SENSOR VOLTAGE (OK DATA) (2.0L)

EXHAUST GAS SENSOR VOLTAGE (OK DATA) (2.0L)

Scheme 72

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Scheme 75

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.

See also:
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