Engine Controls - Tests W/codes: Other Nissan Altima U13

ELECTRONIC CONCENTRATED CONTROL SYSTEM (ECCS)

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

Altima has 2 modes with subdivisions. Before selecting any mode of self-diagnostics, always perform procedures listed in BASIC TESTING article in the ENGINE PERFORMANCE section. Doing so prevents wasted time and false diagnostic results.

Consult Tester

In addition to self-diagnostic capability, all models are equipped with a diagnostic connector for use with Nissan Consult Tester (J-38465). Connector is located on driver's side of center console (above accelerator pedal).

Note. When performing BASIC TESTING procedures, be careful not to erase any diagnostic information stored in ECM 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, ECM 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 ECM memory. If related fault does not reoccur within 50 ignition cycles, related trouble code will be erased from ECM 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 engine control systems. See DIAGNOSTIC ROUTINE table for correct order of procedure.

DIAGNOSTIC ROUTINE

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 engine control system fault has been detected. Not all trouble codes activate CHECK ENGINE light.

SINGLE LED SYSTEM

Self-diagnostic system will operate in 2 modes which are manually selected using a screwdriver through access port on ECM. 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, ECM switches to Mode I.

Mode I (Bulb Check)

Engine is not running in this mode. Turn ignition switch to ON position. Red LED on ECM and CHECK ENGINE light (if equipped) should be lit. If lights 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 engine control system malfunction has occurred and a code has been stored. On Federal vehicles, codes are stored and only Red LED will illuminate when ECM's Central Processing Unit (CPU) malfunctions.

Mode II (Exhaust Gas Monitor)

In Mode II (engine running), 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), left is monitored first. To switch to right, start engine and allow to idle. Turn screwdriver fully clockwise. Wait at least 2 seconds. Turn screwdriver fully counterclockwise. Inspection light will begin to flash. This is Mode II.

DUAL LED SYSTEM

Self-diagnostic system can be operated in any of 5 modes. Modes are manually changed using screwdriver through access port on ECM. With screwdriver turned fully clockwise, inspection lights will begin to flash. Count number of flashes. First flash is Mode I, second flash is Mode II, etc. When desired mode has been indicated, turn screwdriver fully counterclockwise. In different modes, Red LED and Green LED perform different functions.

Mode I (Exhaust Gas Monitor)

This is normal vehicle operating mode. Green LED will indicate loop status. If Green LED is not blinking, vehicle is in open loop or a fault exists with oxygen sensor or sensor circuit. If Green LED is blinking, vehicle is in closed loop. If a malfunction occurs in Mode I, Red LED and CHECK ENGINE light (if equipped) will illuminate, indicating an engine control system malfunction has occurred.

Mode II (Mixture Ratio Feedback Monitor)

In Mode II, both Red LED and Green LED are used to monitor air/fuel mixture feedback control. Green LED will function as in Mode I. In open loop, Red LED and Green LED will remain on or off. For results to be valid, vehicle must be in closed loop. In closed loop, Red LED will indicate if system is running rich (light off), lean (light on) or at ideal air/fuel ratio (blinking synchronized with Green LED).

Mode IV (Switch Check)

This mode is used for checking engine control system's switch status. When idle switch or starter switch is activated, Red LED will come on and go off as status changes. For vehicle speed sensor status, Green LED will remain off when vehicle speed is less than 12 MPH and come on when vehicle speed is greater than 12 MPH.

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 ECM.
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, ECM will switch to Mode I.

1. Turn ignition switch to ON position. Use a screwdriver to turn ECM diagnostic mode selector fully clockwise.
2. Wait for inspection lights to begin flashing. At this time, inspection lights will flash mode options (i.e., one flash for Mode I, 2 flashes for Mode II, etc.). As soon as inspection light flashes desired mode number (3 flashes for self-diagnostic mode), turn mode selector off (fully counterclockwise).
3. If mode selector is kept in ON position (fully clockwise), mode selections will continuously cycle. This cycling will not erase memory.

When Mode II is accessed (engine not running), codes stored in ECM memory will be flashed by CHECK ENGINE light and Red LED on side of ECM. Long flashes (.6 second) indicate 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 codes are read using Red LED and Green LED inspection lights on side of ECM. After selecting Mode III, trouble codes corresponding to mode will start flashing. Trouble codes are indicated by number of flashes from ECM Red LED and Green LED inspection lights. Count number of flashes. Red LED indicates first digit of code, and Green LED indicates second digit of code. For example, 3 flashes of Red LED followed by 2 flashes of Green LED indicate Code 32.

CLEARING CODES

Note. Ensure all diagnostic codes are retrieved from ECM memory before disconnecting battery or erasing stored memory.

Memory Erase (Single LED System)

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.

Memory Erase (Dual LED System)

Stored memory will be erased if battery is disconnected for 24 hours or Mode IV is selected after Mode III has been accessed. However, if mode selector switch is turned fully clockwise, diagnostic modes will continue to cycle until a mode is selected. This cycling does not erase stored memory.

Final Check For All CIRCUIT TESTS

Unless otherwise instructed in code inspection, perform following final check after each repair is completed.

1. Erase diagnostic test Mode II (self-diagnostic results) memory. See «CLEARING CODES»(ref-17456-S40698806842000122900000) under SELF-DIAGNOSTIC SYSTEM.
2. Ensure Code 55 (no malfunction) is displayed in self-diagnostic mode.
3. Perform a test drive.
4. Perform diagnostic test Mode II (self-diagnostic results) again. If results are okay, inspection is complete. If results are not okay, ensure ECM pin terminals and ECM harness connector are not damaged.

Check Input Signal Circuit

Turn ignition off. Disconnect ECM harness connector and A/T control unit harness connector. see scheme 2and (Scheme 35). Ensure continuity exists between following terminals

1. A/T control unit connector terminal No. 10 (Brown/Red wire) and ECM connector terminal No. 42 (Brown/Red wire).
2. A/T control unit connector terminal No. 11 (Blue/Red wire) and ECM connector terminal No. 44 (Blue/Red wire).
3. A/T control unit connector terminal No. 12 (Brown/White wire) and ECM connector terminal No. 12 (Brown/White wire).

(Scheme 36) If continuity is present, perform FINAL CHECK in this article. If continuity is not present, check connectors between ECM and A/T control unit. Repair harness or connectors as necessary and perform FINAL CHECK in this article.

Scheme 35

Scheme 36

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.