Nissan Sentra. Manual - part 746

SEC-12

< SYSTEM DESCRIPTION >

[WITH INTELLIGENT KEY SYSTEM]

SYSTEM

PRECAUTIONS FOR INTELLIGENT KEY SYSTEM

The transponder (the chip for NATS ID verification) is integrated into the Intelligent Key. (For the con-

ventional models, it is integrated into the mechanical key.) Therefore, ID verification cannot be per-

formed by mechanical key only.

In that case, NATS ID verification can be performed when Intelligent Key backside is contacted to

push-button ignition switch while brake pedal is depressed. If verification result is OK, engine can be

started.

OPERATION WHEN INTELLIGENT KEY IS CARRIED

1. When the push-button ignition switch is pressed, the BCM activates the inside key antenna and transmits

the request signal to the Intelligent Key.

2. The Intelligent Key receives the request signal and transmits the Intelligent Key ID signal to the BCM.
3. BCM receives the Intelligent Key ID signal via remote keyless entry receiver and verifies it with the regis-

tered ID.

4. BCM turns ACC relay ON and transmits the ignition power supply ON signal to IPDM E/R.
5. IPDM E/R turns the ignition relay ON and starts the ignition power supply.
6. IPDM E/R turns the starter control relay ON for engine starting in advance.
7. BCM detects the selector lever position and brake pedal operation condition (CVT models), or clutch

pedal operation condition (M/T models).

8. BCM transmits the starter request signal to IPDM E/R and turns the starter relay in IPDM E/R ON if BCM

judges that the engine start condition* is satisfied.

9. Power supply is supplied through the starter relay and the starter control relay to operate the starter motor.

CAUTION:

If a malfunction is detected in the Intelligent Key system, the “KEY” warning lamp on the combina-

tion meter illuminates. At that time, the engine cannot be started.

10. When BCM receives feedback signal from ECM indicating that the engine is started, the BCM transmits a

stop signal to IPDM E/R and stops cranking by turning OFF the starter motor relay. (If engine start is

unsuccessful, cranking stops automatically within 5 seconds.)

CAUTION:

When the Intelligent Key is carried outside of the vehicle (inside key antenna detection area) while

the power supply is in the ACC or ON position, even if the engine start condition* is satisfied, the

engine cannot be started.

*: For the engine start condition, refer to “IGNITION SWITCH POSITION CHANGE TABLE BY PUSH-BUT-

TON IGNITION SWITCH OPERATION”.

OPERATION RANGE

Engine can be started when Intelligent Key is inside the vehicle. However, sometimes engine may not start

when Intelligent Key is on instrument panel or in glove box.

ENGINE START OPERATION WHEN INTELLIGENT KEY IS CONTACTED TO PUSH-BUTTON IG-
NITION SWITCH

When Intelligent Key battery is discharged, NATS ID verification between transponder in Intelligent Key and

BCM is performed when Intelligent Key backside is contacted to push-button ignition switch while brake pedal

is depressed. If the verification result is OK, engine can be started.

IGNITION SWITCH POSITION CHANGE TABLE BY PUSH-BUTTON IGNITION SWITCH OPERA-
TION

The ignition switch position can be changed by the following operations.

NOTE:

• When an Intelligent Key is within the detection area of inside key antenna or when Intelligent Key backside is

contacted to push-button ignition switch, it is equivalent to the operations below.

• When starting the engine, the BCM monitors under the engine start conditions,

CVT models

- Brake pedal operation condition

- Selector lever position

- Vehicle speed

M/T models

- Clutch pedal operation condition

- Vehicle speed

SYSTEM

SEC-13

< SYSTEM DESCRIPTION >

[WITH INTELLIGENT KEY SYSTEM]

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Vehicle speed: less than 4 km/h (2.5 MPH)

Vehicle speed: 4 km/h (2.5 MPH) or more

Emergency stop operation
• Press and hold the push-button ignition switch for 2 seconds or more.
• Press the push-button ignition switch 3 times or more within 1.5 seconds.

NISSAN ANTI-THEFT SYSTEM

Power supply position

Condition

Push-button ignition switch 

operation frequency

CVT models

M/T models

Selector lever

Brake pedal operation 

condition

Clutch pedal operation 

condition

OFF 

→ ACC

—

Not depressed

Not depressed

1

OFF 

→ ACC → ON

—

Not depressed

Not depressed

2

OFF 

→ ACC → ON → 

OFF

—

Not depressed

Not depressed

3

OFF 

→ START

ACC 

→ START

ON 

→ START

P or N position

Depressed

Depressed

1

Engine is running 

→ 

OFF

—

—

—

1

Power supply position

Condition

Push-button ignition switch 

operation frequency

CVT models

M/T models

Selector lever

Brake pedal operation 

condition

Clutch pedal operation 

condition

Engine is running 

→ 

ACC 

—

—

—

Emergency stop operation

Engine stall return oper-
ation while driving 

N position

Not depressed

Depressed

1

SEC-14

< SYSTEM DESCRIPTION >

[WITH INTELLIGENT KEY SYSTEM]

SYSTEM

NISSAN ANTI-THEFT SYSTEM : System Description

INFOID:0000000009756684

SYSTEM DIAGRAM

SYSTEM DESCRIPTION

• The Nissan Anti-Theft System (NATS) prevents the engine from being started by Intelligent Key whose ID is

not registered to the vehicle (BCM). It has higher protection against auto theft involving the duplication of

mechanical keys.

• The ignition key integrated in the Intelligent Key cannot start the engine. When the Intelligent Key battery is

discharged, the NATS ID verification is performed between the transponder integrated with Intelligent Key

and BCM via NATS antenna amp. when the Intelligent Key backside is contacted to push-button ignition

switch while brake pedal is depressed. If the verification result is OK, the engine start operation can be per-

formed by the push-button ignition switch operation.

• Locate the security indicator lamp and always blinks it when the ignition switch is in any position except ON

to warn that the vehicle is equipped with Nissan Anti-Theft System (NATS).

• Up to 4 Intelligent Keys can be registered (including the standard ignition key) upon request from the owner.

• When replacing ECM, BCM or Intelligent Key, the specified procedure (Initialization and registration) using

CONSULT is required.

• Possible symptom of NATS malfunction is “Engine can not start”. This symptom also occurs because of

other than NATS malfunction, so start the trouble diagnosis according to 

GI-35, "Work Flow"

.

• If ECM other than genuine part is installed, the engine cannot be started.

For ECM replacement procedure, refer to 

EC-485, "Removal and Installation"

.

PRECAUTIONS FOR KEY REGISTRATION

ALKIA2975GB

SYSTEM

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< SYSTEM DESCRIPTION >

[WITH INTELLIGENT KEY SYSTEM]

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• The ID registration is a procedure that erases the current NATS ID once, and then registers a new ID. There-

fore before starting the registration operation, collect all registered Intelligent Keys from the customer.

• When registering the Intelligent Key, perform only one procedure to simultaneously register both IDs (NATS

ID and Intelligent Key ID).

SECURITY INDICATOR LAMP

• Security indicator lamp warns that the vehicle is equipped with NATS.

• Security indicator lamp always blinks when the ignition switch is in any position other than ON.

NOTE:

Because security indicator lamp is highly efficient, the battery is barely affected.

ENGINE START OPERATION WHEN INTELLIGENT KEY IS CONTACTED TO PUSH-BUTTON IG-
NITION SWITCH

1. When brake pedal is depressed while selector lever is in the P position (CVT models), or selector lever is

in the Neutral position (M/T models), the BCM activates NATS antenna amp. that is located behind push-

button ignition switch.

2. When Intelligent Key (transponder built-in) backside is contacted to push-button ignition switch, BCM

starts NATS ID verification between BCM and Intelligent Key (transponder built-in) via NATS antenna

amp.

3. When NATS ID verification result is OK, buzzer in combination meter sounds and BCM transmits the

result to ECM.

4. BCM turns ACC relay ON and transmits ignition power supply ON signal to IPDM E/R.
5. IPDM E/R turns the ignition relay ON and starts the ignition power supply.
6. IPDM E/R turns the starter control relay ON for engine starting in advance.
7. BCM detects that the selector lever position and brake pedal operation condition (CVT models), or clutch

pedal operation condition (M/T models).

8. BCM transmits starter request signal to IPDM E/R and turns the starter relay in IPDM E/R ON if BCM

judges that the engine start condition* is satisfied.

9. Power supply is supplied through the starter relay and the starter control relay to operate the starter motor.
10. When BCM receives feedback signal from ECM indicating that the engine is started, BCM transmits a

stop signal to IPDM E/R and stops cranking by turning off the starter motor relay. (If engine start is unsuc-

cessful, cranking stops automatically within 5 seconds.)

*: For the engine start condition, refer to “IGNITION SWITCH POSITION CHANGE TABLE BY PUSH-BUT-

TON IGNITION SWITCH OPERATION” below.

IGNITION SWITCH POSITION CHANGE TABLE BY PUSH-BUTTON IGNITION SWITCH OPERA-
TION

The ignition switch position can be changed by the following operations.

NOTE:

• When an Intelligent Key is within the detection area of inside key antenna or when Intelligent Key backside is

contacted to push-button ignition switch, it is equivalent to the operations below.

• When starting the engine, the BCM monitors under the engine start conditions,

CVT models

- Brake pedal operation condition

- Selector lever position

- Vehicle speed

M/T models

- Clutch pedal operation condition

- Vehicle speed

Vehicle speed: less than 4 km/h (2.5 MPH)

Power supply position

Condition

Push-button ignition switch 

operation frequency

CVT models

M/T models

Selector lever

Brake pedal operation 

condition

Clutch pedal operation 

condition

OFF 

→ ACC

—

Not depressed

Not depressed

1

OFF 

→ ACC → ON

—

Not depressed

Not depressed

2