Dualstage SRS Airbag System General

In this system, when the front airbag sensors and airbag sensor assembly detect a front collision, the airbag sensor assembly judges the extent of impact, seat position and whether or not the seat belts are fastened, thus optimizing the airbag inflating output by delaying the inflation timing of the 2nd initiator and the 1st initiator.

Seat Position Sensor 1) General

The seat position sensor is mounted on the upper rail portion of the driver seat rail, and includes a Hall IC and a magnet. This sensor is used to detect the sliding position of the driver seat.

Corolla Driver Seat Position Sensor

2) Operation

When the seat is in the rearward position, the lower rail portion of the seat rail is close to the seat position sensor. When it is in the forward position, the distance between the lower rail portion and the sensor becomes larger.

Thus, the magnetic flux of the magnet inside the seat position sensor varies depending on the seat position. The Hall IC detects this variation and outputs signals to the airbag sensor assembly.

Toyota Corolla Srs Airbag System
Seat position is rearward Seat position is forward

Service Tip

Follow the procedure indicated below to install the seat position sensor.

1) Insert a 1.5 mm (0.06 in.) feeler gauge between the seat position sensor and the lower rail portion.

2) Tighten the mounting bolt to the specified torque with the seat position sensor pushed down as shown.

For details, see the 2007 Camry Repair Manual (Pub. No. RM0250U).

Seat Position Sensor

Seat Position Sensor

1.5 mm (0.06 in.) Lower Rail


Seat Belt Buckle Switch

The seat belt buckle switch detects whether or not the seat belt is fastened.

► The non-contact type switch is composed of a Hall IC and two magnets, installed into the front seat inner belt assembly.

► The ejector inside the front seat inner belt assembly and the plate installed to the ejector move when the seat belt is removed or inserted. The movement of the plate changes the magnetic flux density of the magnet.

► The Hall IC detects the changes in the magnetic flux density in accordance with the seat belt removal or insertion, and outputs a signal to the airbag sensor assembly (for driver seat) and occupant classification ECU (for front passenger seat).


Hall IC



Hall IC



Seat belt not fastened

Hall IC


Seat belt fastened

Magnet Flux


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