System Description

SYSTEM DIAGRAM

Courtesy of NISSAN NORTH AMERICA, INC.

SYSTEM DESCRIPTION

Supplemental Restraint System (SRS) activates air bag module and seat belt pre-tensioner when it detects a frontal collision or a side collision that is more than the specified limit.

Together with other safety devices, it reduces the impact that occupant receives when vehicle collision occurs.

Air bag diagnosis sensor unit supplies power supply to air bag module and pre-tensioner seat belt when deceleration that is more than the specified limit is detected by G sensor in air bag diagnosis sensor unit, crash zone sensor, satellite sensor.

Air bag module is composed of electric igniter (squib), filter, pyrotechnic material, and gas generating material. When air bag module receives a signal from air bag diagnosis sensor unit, air bag module ignites pyrotechnic material using electric igniter (squib) so that gas generating material generates high temperature nitrogen gas. The gas through filter activates air bag. At the same time, pre-tensioner seat belt receives power supply from air bag diagnosis sensor unit, gas generator is activated, and then gas is generated.

Balls in pipe are moved according to generated gas pressure and strike pinion gear on ELR shaft.

ELR shaft rotates and retracts seat belt.

AIR BAG DIAGNOSIS SENSOR UNIT FUNCTIONS

Air bag diagnosis sensor unit has the following functions.

Detects a collision and supplies the energy for deploying air bag and seat belt pre-tensioner.
Detects and records electrical malfunction in air bag system and seat belt pre-tensioner system, and turns air bag warning lamp ON.
Detects and records the deployment of air bag and seat belt pre-tensioner, and turns ON air bag warning lamp.
Indicates malfunctioning portion via the number of blinks from the air bag warning lamp in the diagnosis mode.
Indicates the malfunction record via CONSULT.
Transmits collision detection signal to BCM and other ECU when a collision is detected (collision detection output function).

SRS AIR BAG WARNING LAMP

Detects electrical malfunction in air bag system and seat belt pre-tensioner system, and turns SRS air bag warning lamp ON.
Detects deployment malfunction in air bag system and seat belt pre-tensioner system, and turns SRS air bag warning lamp ON.
Air bag diagnosis sensor unit warns the driver by turning SRS air bag warning lamp ON when air bag diagnosis sensor unit detects battery low voltage. SRS air bag warning lamp turns ON when a voltage value at which air bag diagnosis sensor unit cannot operate normally (9 V or less) is detected. After starting to turn ON, SRS air bag warning lamp turns OFF when air bag diagnosis sensor unit detects the normal value of battery voltage.
Air bag diagnosis sensor unit warns the driver by turning SRS air bag warning lamp ON when air bag diagnosis sensor unit detects battery high voltage. SRS air bag warning lamp turns ON when a voltage value at which air bag diagnosis sensor unit cannot operate normally (16 V or more) is detected. After starting to turn ON, SRS air bag warning lamp turns OFF when air bag diagnosis sensor unit detects the normal value of battery voltage.

SRS air bag warning lamp operation	SRS condition
Courtesy of NISSAN NORTH AMERICA, INC.	No malfunction is detected
Courtesy of NISSAN NORTH AMERICA, INC.	Air bag is deployed Seat belt pre-tensioner is deployed Air bag diagnosis sensor unit is malfunctioning Air bag power supply circuit is malfunctioning SRS air bag warning lamp circuit is malfunctioning Each sensor is malfunctioning Each module is malfunctioning Battery voltage is low (9 V or less) or high battery voltage (16 V or more)
Courtesy of NISSAN NORTH AMERICA, INC.	Air bag diagnosis sensor unit is malfunctioning SRS air bag warning lamp circuit is malfunctioning Combination meter is malfunctioning

COLLISION MODES

The operation of SRS is different depending on the collision modes applications. For example, the driver air bag module, passenger air bag module, seat belt pre-tensioner and lap pre-tensioner are activated in a frontal collision.

SRS configurations that are activated for the following collision modes.

x: Apply -: Not apply

SRS configuration	Frontal collision	Rear collision	Left side collision	Right side collision
Driver air bag module	x	-	-*1	-*1
Passenger air bag module	x	-	-*1	-*1
Seat belt pre-tensioner LH	x	-*1	x	-*1
Seat belt pre-tensioner RH	x	-*1	-*1	x
Lap pre-tensioner LH	x	-*1	-*1	-*1
Lap pre-tensioner RH	x	-*1	-*1	-*1
Side air bag module LH	-*2	-	x	-*2
Side air bag module RH	-*3	-	-*3	x
Curtain air bag module LH	-*2	-	x	-*2
Curtain air bag module RH	-*3	-	-*3	x
Collision detection output function	x	x	x	x

*1: SRS may be activated when an excessive impact is applied toward the front of the vehicle.

*2: SRS may be activated when an excessive impact is applied toward the left of the vehicle.

*3: SRS may be activated when an excessive impact is applied toward the right of the vehicle.

OCCUPANT DETECTION SYSTEM

This Occupant Detection System has the following functions.

Suppress the deployment of front passenger air bag when front passenger seat is empty, or when occupied by child and child-seat. Turns ON front passenger air bag OFF indicator when front passenger seat is occupied by child-seat and child.
Indicates malfunction portion with blinking times of air bag warning lamp in diagnosis mode.
Indicates the malfunctioning record by CONSULT.
When "zero point reset" for occupant detection system is incomplete, CONSULT indicates that "zero point reset" is incomplete.
This function is applied to NISSAN genuine parts only.

NOTE:

Operation of air bag diagnosis sensor unit when air bag diagnosis sensor unit receives information from Occupant Detection System.
Even if zero point reset is "complete", always perform zero point reset after the removal and installation of seat or the removal of control unit harness connector.

Status (front passenger seat)	Passenger air bag	Front passenger air bag OFF indicator	Air bag warning lamp
Empty	Suppress	ON	OFF
An object	Suppress	ON	OFF
Child/ child-seat	Suppress	ON	OFF
Adult	Enable to deploy	OFF	OFF
Malfunction	Suppress	ON	ON
Zero point reset Not yet performed (NISSAN genuine parts only)	Suppress	ON	ON

Active Vent Function

Air bag diagnosis sensor module opens vent of passenger side air bag module by passenger side occupant detecting condition if necessary. The pressure of the developed air bag falls, and the passenger side occupant is take care of appropriately.