- Clockspring
- Steering wheel
- Driver air bag
- Air bag module
- Passenger air bag
- Seat belt pre-tensioners (RH illustrated)
Supplemental Restraint Systems (SRS)
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WARNING: Air bags inflate with great force, in a fraction of a second. If a vehicle occupant is too close to the air bag, less than 10 in (255 mm) or incorrectly positioned, they could be killed or seriously injured. |
The vehicle is equipped with a pyrotechnic, pre-tensioner seat belt system that also features a load-limiting capability. In addition to this, each occupant seating position is protected by a single stage air bag system designed to work in conjunction with the seat belts. When triggered, the Supplemental Restraint System (SRS) tightens the seat belts to better protect the occupants and inflates the air bags to cushion the upper part of their bodies.
These devices supplement, but DO NOT replace, the protection afforded to vehicle occupants by the seat belts. Seat belts have proven to be the single most effective safety device, and should always be worn, even on short journeys. Properly worn seat belts also ensure that the seat occupant is in the best position for full effectiveness of the air bag.
Although the air bags and pre-tensioners are designed to be electrically triggered, they are pyrotechnic components and certain conditions may cause them to malfunction. Correct transport, storage and repair methods must be used.
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WARNING: Accidental deployment will potentially cause damage and personal injury. Always refer to the Owner Information for correct use of the occupant restraint systems and to the Service Manual for correct fitment, repair and disposal of system components. |
NOTE: The SRS will deploy only in moderate to severe frontal and near frontal collisions, and is not designed to be triggered in rollover, rear or low speed frontal collisions, or in some types of side impacts.
The SRS is controlled by an air bag module, which includes fault detection and warning circuits. In the event of a fault being detected a warning indicator in the instrument pack will notify the driver. Additionally, Diagnostic Trouble Codes (DTCs) may be retrievable, via a diagnostic tool, through the standard diagnostic socket located in the driver’s footwell.
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WARNING: Proper operation of the SRS system requires that any repairs to the vehicle structure return it to its original production configuration. Deployment or any visible damage to the SRS components and/or their respective mounting brackets requires replacement, not repair. |
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WARNING: Handle the air bag module with great care. Never strike or jar the module as this could cause air bag deployment and result in personal injury or improper operation of the air bags. |
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WARNING: All air bag module and mounting bracket bolts must be correctly installed and tightened to ensure proper security and operation. |
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WARNING: Never power up the SRS when the air bag module is not properly mounted and secured, since the module is easily triggered when not attached and could result in deployment causing personal injury. |
The air bag module is bolted to a dedicated bracket riveted to the top of the passenger side dash frame and is accessible only after removal of the upper dash panel. Location and orientation of the module is critical to its correct operation and no modifications should be made to it or its mountings.
The air bag module is calibrated specifically to the vehicle and contains an accelerometer to measure forces affecting the vehicle and circuits for determining the resistance, and therefore condition, of the other SRS components. A safing sensor within the module provides an electro-mechanical switch as a safety backup to the accelerometer circuit. A ground wire in the harness connector provides the ground through the front negative post. The module casing is also grounded through the same wire.
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WARNING: When carrying a live air bag, make sure the bag and trim cover are pointed away from you. In case of an accidental deployment, the bag will then deploy with minimal chance of injury. |
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WARNING: When placing a live air bag on a bench or other surface, always face the bag and trim cover upwards, away from the surface. This is necessary so that a free space is provided to allow the air bag to expand in the unlikely event of accidental deployment. Otherwise, personal injury may result. |
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WARNING: Never carry the air bag by the wires or connector on the underside of the module. |
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WARNING: DO NOT use or attempt to repair a damaged air bag, and NEVER apply any electrical power to it, except as specified in the diagnostic procedures. |
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WARNING: Failure to follow proper air bag disposal procedures can result in air bag deployment which may cause personal injury. Undeployed air bags MUST NOT be disposed of through normal refuse channels. The undeployed air bag contains substances that can cause severe illness or personal injury if the sealed container is damaged during disposal. Disposal in any manner inconsistent with proper procedures may be a violation of federal, state and/or local laws. |
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WARNING: Safety precautions must be observed when handling a deployed air bag. After deployment, the air bag surface may contain a white packing powder used to ease deployment, together with a small amount of sodium hydroxide dust, a by-product of the sodium azide reaction during deployment. This can be irritating to the skin if left on for an extended period of time. Always wear gloves and safety glasses when handling a deployed air bag, and wash your hands with a mild soap and water afterwards. |
The driver air bag is fitted under a cover, on the steering wheel boss, where it is secured by two bolts. The driver air bag cover is scored on its inner surface to provide seams, which split when the air bag is deployed. Connection to the air bag module is through the clockspring on the steering column.
The passenger air bag is fitted under a cover on the facia in front of the passenger seat. The passenger air bag cover hinges on deployment to allow the air bag to expand.
Each air bag comprises:
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WARNING: Seat belt pre-tensioners can only aid safety if the vehicle occupants are wearing seat belts correctly. |
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WARNING: Failure to comply with the instructions, safety standards and operating procedures, as described in the Tesla documentation, may cause vehicle damage and/or personal injury. |
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WARNING: Following an impact in which the pre-tensioning element is activated, the seat belt assembly is rendered inoperable. The vehicle should not be driven until the belt assembly has been renewed. |
One pre-tensioner is fitted to each of the inertia seat belt reels on the inner side of each B-post. The pre-tensioners are electrically triggered, pyrotechnic devices, which instead of generating gas to fill a fabric bag as with the air bags, use the gas to move a piston and rack gear.
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WARNING: The clockspring MUST be replaced after SRS deployment even if there is no visible damage. |
The clockspring is encapsulated into a plastic cassette comprising outer and inner housings with integral connectors. The cassette contains a flat ribbon type flexible cable with four wires carrying out the following functions:
The inner housing is attached to the steering wheel by two screws and the outer is positively located to the column lever assembly by a spring loaded pin. The clockspring connects to the driver air bag module and horn buttons on the steering wheel and to the front harness at the steering column via two multiplugs.
The 4-wire cable from the clockspring joins the front harness at a dedicated connector, which incorporates a shorting bar. To separate the two connectors it is necessary to slide the retaining clip away from the connector block. The two halves of the connector can now be pulled apart. As the top and bottom parts separate, a spring-loaded plate moves forward to form a bridge between the two air bag terminals. When in contact the plate completes an endless circuit, thus reducing the possibility of the driver air bag being accidentally deployed.
As the two parts of the connector are reconnected, the spring-loaded plate is pushed back, breaking the circuit and allowing normal operation of the air bag system.
The air bag warning indicator (arrowed) is located in the instrument pack below the speedometer.
The SRS system connections are all hardwired and operate at 12V. In the event of a collision, the inertia switch will trip, the doors will unlock and the operation of the vehicle electrical systems will be inhibited.
The air bag module has the following functions:
Impact signals are generated by the acceleration sensor as a voltage, which is proportional to the impact acceleration experienced. The signal from the acceleration sensor is inhibited if the safing sensor does not detect an impact.
If the safing sensor and accelerometer both signal a deceleration force, the voltage is filtered and digitized before being interpreted by software in the air bag module, which determines whether the force is above pre-determined levels. If an impact is below the defined limits, no further action is taken by the air bag module. If the air bag module determines that the SRS system should be deployed it switches the 12V from the air bag and pre-tensioner modules to ground, causing current to flow through the module initiators simultaneously.
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WARNING: If the air bag warning indicator does not operate as described, a fault in the SRS system is indicated. The air bags may not inflate correctly or at all, or may inflate without warning. The system should be interrogated using the diagnostic tool, the fault diagnosed and repaired immediately. |
NOTE: The warning indicator will be activated without air bag module deployment in the following situations:
When the key first turned ON, the air bag module illuminates the warning indicator lamp in the instrument pack for approximately 6 seconds. If the lamp does not illuminate there is a fault in the indicator circuit. If the lamp remains illuminated after 6 seconds, or if it illuminates during driving, then an SRS fault is indicated. Both fault types need to be investigated using a diagnostic tool and repaired immediately.
The air bag module will also illuminate the warning indicator when a diagnostic tool is connected to the diagnostic socket, or on deployment of the SRS.
As the air bag module monitors the SRS systems, it compares results with pre-determined parameters and flags a fault if results are outside limits. Faults are stored within the air bag module for retrieval and/or clearance with a diagnostic tool. Some faults will also illuminate the air bag warning indicator.
The air bag module stores three types of fault code:
| Fault Code Type | Storage Type | Clearance Method | |
| 1 | Current (Data stored in the current cycle) | Volatile RAM | Key Off |
| 2 | Historic (Previously stored data) | Electrically Erasable Programmable Read-Only Memory (EEPROM) | Clear with diagnostic tool |
| 3 | Crash Data | Permanent | Replace |
NOTE: Data stored in the current cycle that does not get written to the EEPROM will be lost as soon as the key is turned OFF.
Neither the seat belt pre-tensioners nor the air bags should be activated by the air bag module as long as the diagnostic mode is active.
A nominal supply voltage of 12V is supplied to the air bag module when the key is in the ON position. Voltage supplies above or below 12V will affect the operation of the SRS system. At voltages below 10.5V, system fault detection and readiness will be progressively delayed. Air bag deployment will only occur if the supply voltage is between 8V to 16V. Pre-tensioner deployment will only occur if the supply voltage is between 10V to 16V.
NOTE: High or low supply voltages will cause the illumination of the instrument pack warning indicator but will not trigger DTCs. If the correct supply voltage is achieved the warning indicator will be extinguished after a short delay.
Additional functions maintain an energy reserve in case of vehicle battery power interruption. Energy reserve capacitors allow SRS deployment if the vehicle battery power supply is interrupted during the time of vehicle impact. The capacitors support acceleration sensing and air bag initiation capability for a minimum of 150 ms after a loss of external power supply, provided that the capacitors had been supplied with, and charged by more than 8V for at least 20 seconds. Higher supply voltages take less time to charge the capacitors.
After removal of the power supply the capacitors will discharge. Within a maximum of 2 seconds no initiation of air bags should be possible.
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WARNING: Always follow the Service Manual 'Air Bag and SRS Precautions' and the correct procedures for working on air bag and SRS components. Persons working on air bag and SRS systems must be fully trained and have been issued with copies of the Safety guidelines. |
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WARNING: In some conditions the air bag module can maintain sufficient voltage to cause an air bag deployment for up to 30 seconds after switching the key OFF. |
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WARNING: Ensure that the SRS system is fully discharged before commencing work on the system. |
When the air bag module triggers the initiators the gas generating material becomes heated and ignites. This inflates the bags in a fraction of a second, causing them to burst through past the air bag covers into the passenger compartment, where they inflate fully to provide a cushion protecting the occupants. Vents in the air bag then allow the gas to escape and the air bags deflate very quickly to minimize the interference between the driver and the vehicle controls. The full cycle takes less than 1 second.
When triggered by the air bag module the gas generating material in the inflator produces gas, which expands and forces a piston downwards. As the piston moves, it contacts a rack gear, which in turn causes a pinion on the end of the seat belt reel to rotate, rewinding any slack in the seat belt webbing. A torsion bar between the pinion and reel limits the force applied to the occupant.
Under normal operation, the rack is fully raised and disengaged from the pinion, allowing normal spooling of the reel for belt withdrawal and retraction. Once used, the pre-tensioners permanently lock the reel to indicate that they need to be replaced. In the locked condition the belt webbing cannot be withdrawn from or wound onto the reel.
As the steering wheel rotates, the ribbon cable in the clockspring cassette winds, or unwinds, itself onto the inner housing, maintaining an unbroken circuit between the steering wheel and column. The inner rotary housing can turn a maximum of 4.2 revolutions in relation to the outer housing.
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CAUTION: It is important that the locating pin is correctly fitted to the column lever assembly, or the ribbon cables may become over-tightened, causing the cables to snap. |