Nissan Sentra manuals

Nissan Sentra Service Manual: Ecu diagnosis information


Reference Value



Example: The ignition timing shown by the timing light may differ from the ignition timing displayed on the data monitor. This occurs because the timing light shows a value calculated by ECM according to signals received from the cam shaft position sensor and other sensors related to ignition timing.

For outlines of following items, refer to EC-66, "CONSULT Function".

*1: Accelerator pedal position sensor 2 signal and throttle position sensor 2

*1: Accelerator pedal position sensor 2 signal and throttle position sensor 2 signal are converted by ECM internally. Thus, they differ from ECM terminals voltage signal.

*2: Before measuring the voltage, confirm that the battery is fully charged. Refer to PG-4, "How to Handle Battery".

Terminal layout

Physical values

Physical values


Average voltage for pulse signal

(Actual pulse signal can be confirmed by oscilloscope.)Average voltage for pulse signal
(Actual pulse signal can be confirmed by oscilloscope.)

*Before measuring the terminal voltage, confirm that the battery is fully charged. Refer to PG-4, "How to Handle Battery".

Fail Safe


Detected items

Engine operating condition in fail-safe mode


Reference page

Malfunction indicator circuit Engine speed will not rise more than 2,500 rpm due to the fuel cut When there is an open circuit on MIL circuit, the ECM cannot warn the driver by lighting up MIL when there is malfunction on engine control system.

Therefore, when electrical controlled throttle and part of ECM related diagnoses are continuously detected as NG for 5 trips, ECM warns the driver that engine control system malfunctions and MIL circuit is open by means of operating fail safe function.

The fail safe function also operates when above diagnoses except MIL circuit are detected and demands the driver to repair the malfunction.

EC-467, "Component Function Check"



When a DTC is detected, ECM executes a mode (in the Fail-safe mode) applicable to the DTC. The fail-safe mode has the preset traveling control mode (accelerator angle variation and engine output limit) and device fix mode.

Fail safe mode

Vehicle behavior

Traveling control mode Accelerator angle variation control ECM controls the accelerator pedal depression speed to make it slower than actual speed. This causes a drop in accelerating performance and encourages the driver to repair malfunction.


ECM does not control the accelerator pedal releasing speed.

Engine output control ECM reduces the engine output, according to the rise in engine speed. This reduces the vehicle speed to encourage the driver to repair malfunction.
Device fix mode
  • This mode fixes the IVT control solenoid valve and the EVT control solenoid valve in the reference position.
  • The intake manifold runner control valve motor is turned OFF (intake manifold runner control valve opens).

Fail Safe Pattern

Fail Safe List

Fail Safe List

DTC Inspection Priority Chart

DTC Inspection Priority Chart

If some DTCs are displayed at the same time, perform inspections one by one based on the following priority chart.

DTC Index

DTC Index

1*-1st trip DTC No. is the same as DTC

1*-1st trip DTC No. is the same as DTC No.

2*-This number is prescribed by SAE J1979/ ISO 15031-5.

3*-In Diagnostic Test Mode II (Self-diagnostic results), this number is controlled by NISSAN.

4*-Refer to EC-151, "Description".

5*-The trouble diagnosis for this DTC needs CONSULT

6*-When the ECM is in the mode that displays SRT status, MIL may blink. For details, Refer to EC-63, "On Board Diagnosis Function".

7*-SRT code will not be set if the self-diagnostic result is NG.

8*-When the fail-safe operations for both self-diagnoses occur, the MIL illuminates.


10*-This self-diagnosis is not for ECM power supply circuit, even though “ECM BACK UP/CIRCUIT” is displayed on CONSULT screen.

Test Value and Test Limit

The following is the information specified in Service $06 of SAE J1979/ISO 15031-5.

The test value is a parameter used to determine whether a system/circuit diagnostic test is OK or NG while being monitored by the ECM during self-diagnosis. The test limit is a reference value which is specified as the maximum or minimum value and is compared with the test value being monitored.

These data (test value and test limit) are specified by On Board Monitor ID (OBDMID), Test ID (TID), Unit and Scaling ID and can be displayed on the GST screen.

The items of the test value and test limit will be displayed with GST screen which items are provided by the ECM. (e.g., if bank 2 is not applied on this vehicle, only the items of bank 1 are displayed)

Wiring diagram

Consult function
FUNCTION Diagnostic test mode Function Self Diagnostic Results Self-diagnostic results such as 1st trip DTC, DTCs and 1st trip freeze frame data or freeze frame data can ...

Wiring diagram
Engine control system Wiring Diagram ...

Other materials:

Push-button ignition switch illumination circuit
Description Provides the power supply and the ground to control the push-button ignition switch illumination. Component function check 1.Check push-button ignition switch illumination operation Consult active test Turn the ignition switch ON. Select engine sw illumi of bcm (intelligen ...

System description
Component parts Body control system Body control system : component parts location BCM (view with instrument panel removed) Combination switch reading system Combination switch reading system : component parts location BCM (view with combination meter removed) Combination s ...

Warning chime system Warning chime system : system diagram Warning chime system : system description Description The buzzer for warning chime system is installed in the combination meter. The buzzer sounds when the combination meter receives a buzzer output signal from the bcm. Th ...

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