Airbag Equipment

The 911 Carrera comes with a driver and passenger airbag system as standard equipment (also for right-hand drive).
The modified airbag unit is built into the steering wheel.




The airbag unit is mounted with 2 self-locking screws (Torx T-30). These screws have to be replaced every time whenever assembly operations are carried out on the unit. Tightening torque: 10 Nm.




The retaining boss for the airbag unit is made of thermoplastic material. When the unit is ignited, the boss is torn open at a predetermined design point, folds open and releases the airbag.

The airbag is made of non-coated polyamide fabric. Tear seams in the internal part of the bag ensure that the ideal cushion shape is produced when expanded. The airbag has a volume of approximately 64 liters.




Airbag Unit, Reverse View
The airbag unit consists of the retaining cushion made of thermoplastic material, the integral airbag and the gas generator with its retaining plate.




Gas Generator, Design
1 Combustion chamber with solid fuel
2 Ignition pellet and charge
3 Outlet channels and filter
4 Electrical connection

Gas Generator, Operation
The combustion chamber of the gas generator contains a solid fuel charge pressed into tablets. The ignition pellet located in the center of the gas generator is filled with an ignition charge of its own.
When an electrical pulse (ignition pulse) is transmitted, the solid fuel ignites in fractions of a second. The combustion of the fuel produces nitrogen.
The gas flows through side channels that also serve to filter and cool the gas into the folded bag.
The filters retain any particles produced by combustion and reduce the temperature of the gas.
The airbag is filled with gas and tears the boss apart at the predetermined position. The total time required from the ignition to full expansion of the bag is 30 milliseconds.
The gas escapes through the 40 mm dia. outlet at the rear of the bag.




Airbag Unit, Passenger Side
The airbag unit on the passenger side consists of the pipe gas generator, the airbag made of noncoated polyamide fabric (volume approx. 140 liters), the thermoplastic boss plate, the wiring loom with its plugs and the mounting consoles. The sides of the airbag are permeable and allow passage of the gas.




Pipe Gas Generator, Design
1 Combustion chamber with solid fuel
2 Ignition pellet with charge
3 Ignition tube
4 Filter material
5 Outlets









Control Unit
The complete actuation electronics and the system monitor are integrated into the control unit. The earlier front sensors installed in the front of the car have been deleted.
The installation position is determined by the type of mounting used. The unit is mounted with shear nuts (1/4" socket head). Use Special Tool 9259 to undo the nuts.

Purpose Of The Control Unit
- Crash detection and determination of the ignition timing point
- Ignition of the airbag system
- System monitoring with fault indication and storage
- Diagnosis
- Programming
- System readiness is indicated when the airbag warning lamp goes dark approximately 4 seconds after ignition is switched ON.

Features Of The Control Unit
- 30-pin connecting plug
- Airbag warning lamp lights up when the unit plug is not connected
- With new units the airbag warning lamp flashes until the car type and equipment have been confirmed with the System Tester
- Constant display of crash relevant faults (a)
- Display of noncrash relevant faults (b) for 2 minutes after ignition is switched on
- Faults in the system cannot be erased
- Replacement of the control unit is not required until the system has been triggered for the 3rd time
- Diagnostic capability with System Tester 9288

(a) Faults that can lead to activation failure or incorrect activation
(b) Faults that cannot influence the airbag system

NOTE: The airbag control unit must not be removed with the plug still connected. Wait for at least 1 min. after switching the ignition off (battery disconnected) and disconnecting the plug connector before continuing work on the airbag system.





Contact Unit
The contact ring and the actual contact for the horn are omitted on the new unit. The signal is transmitted via the contact unit. The contact unit has no direct contact to the steering shaft. The rotary effect is achieved via the lugs in the contact unit and the corresponding recesses in the steering wheel.




In order to prevent inadvertent turning of the contact unit after the steering wheel has been removed, the contact unit locks automatically when the steering wheel is taken off.
The contact unit is designed for a maximum of 4.5 full turns. The front wheels should be in the straight-ahead position when fitting or removing the steering wheel.