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Nissan Sentra B18 (2020-2025) Service Manual: System

Srs Air Bag Control System

System Description

System Description

SYSTEM DIAGRAM

System Description

  • The air bag deploys if the air bag diagnosis sensor unit is activated while the ignition switch is in the ON or START position.

  • The collision modes for which supplemental restraint systems are activated are different among the SRS systems. For example, the driver air bag module, front passenger air bag module and front seat belt pre-tensioners are activated in a frontal collision but not in a side collision.

SRS Collision Modes

SRS configuration

Frontal collision

Left side collision

Right side collision

Rollover

Driver air bag module

x

Front passenger air bag module

x

Left knee air bag module

x

Right knee air bag module

x

Front LH seat belt pre-tensioner

x

x

Front RH seat belt pre-tensioner

x

x

Rear LH seat belt pre-tensioner

x

x

Rear RH seat belt pre-tensioner

x

x

Front LH side air bag module

x

Front RH side air bag module

x

Rear LH side air bag module

x

x

Rear RH side air bag module

x

x

LH side curtain air bag module

x

x

RH side curtain air bag module

x

x

Occupant Classification System

System Description

System Description

SYSTEM DIAGRAM

System Description

The occupant classification system (OCS) identifies different size occupants, out of position occupants, and detects if a child seat is present in the front passenger seat. The OCS control unit (2) receives inputs from the occupant classification system sensors (1) (located inside the passenger seat cushion assembly). Depending on classification of the passenger, the OCS sends a signal to the air bag diagnosis sensor unit. The air bag diagnosis sensor unit uses this signal and the front seat belt buckle switch RH signal to determine deployment or non deployment of the front passenger air bag module in the event of a collision. Depending on the signals received, the air bag diagnosis sensor unit can disable the front passenger air bag module completely. The OCS (weight sensors) must be set to zero point using CONSULT after servicing the OCS system.

Note:
  • CONSULT can be used to confirm when “zero point reset” for OCS is complete.

  • Always perform zero point reset after the removal and installation of the seat or when disconnecting the OCS control unit harness connector even if zero point reset has been completed in the past.

  • If zero point reset is incomplete, the passenger air bag will be disabled and the passenger air bag off indicator will be ON.

  • In case of customer concern, CONSULT can be used to confirm the passenger air bag status (readiness).

Passenger Air Bag Status Conditions

Front Passenger Seat

(Condition)

PASS AIR BAG OFF Indicator

(Status)

Passenger Air Bag Status

(Readiness)

CONSULT Display

Seat occupied

OFF

Active (enabled)

ON

Seat occupied NOTE

ON

Deactivated (disabled)

OFF

Seat empty

OFF

Deactivated (disabled)

OFF

Note:

Passenger does not meet Occupant Classification System specifications for passenger air bag activation.

Seat Belt Warning Lamp System

System Description

System Description

SYSTEM DIAGRAM

System Description

The seat belt warning lamp (1) will remind the driver if the driver or front passenger seat belt should be buckled. The system works in conjunction with the occupant classification system. Refer to System Description.

Seat Belt Warning System Operation

Driver seat status

(Ignition switch ON)

Passenger seat status

Front seat belt buckle switch LH status

Front seat belt buckle switch RH status

Seat belt warning lamp

Seat occupied

Seat occupied

Buckled

Buckled

Off

Unbuckled

On

Seat unoccupied

Off

Unbuckled

On

    Component Parts. Srs Air Bag Control System
    Srs Air Bag Control System Component Parts Location Component Parts Location A. RH front passenger seat (view with seat removed from Nissan Sentra vehicle) B. Driver’s door ar...
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