Electrical Diagrams
Airbag Diagrams:
Airbag Components:
Locations of components
1 Battery
On the left-hand side of the engine compartment
7 Earthing point
On the radiator cross-member
20 Ignition switch
On the centre console between the front seats
22A Fuse holder
In the electrical distribution box, in the engine compartment, on the left-hand wheel housing
47E Charging warning lamp
47K SHIFT UP warning lamp
47T SRS Airbag warning lamp
In the combined instrument
57 3-pole connector
One at the right-hand front sensor one at the left-hand front sensor
58 12-pole connector
On the inside of the knee shield, to the left of the steering column
59 2-pole connector (Convertible)
In the electrical distribution box in the engine compartment, on the left-hand wheel housing
75 Distribution block
In the engine compartment, forward of the battery
98 10-pole connector
One (black) on the inside of the knee shield, to the left of the steering column
One at the electronic unit
123 4-pole connector
One at the electronic unit
One black (left-hand front sensor)
One grey (right-hand front sensor)
152A 29-pole white connector
152B 29-pole red connector
In the electrical distribution box in the engine compartment, on the left-hand wheel housing. The connectors are accessible from the interior of the car.
158 Negative distribution terminal
In the electrical distribution box in the engine compartment, on the left-hand wheel housing
211 Earthing point
On the gearbox
330 10-pole airbag test connector
In the centre console, under the rubber bellows, forward of the gear lever
331 Electronic unit for the airbag
To the left, under the fascia
332A Sensor, left-hand
In the engine compartment, forward of the left-hand wheel housing
332B Sensor, right-hand
In the engine compartment, forward of the right-hand wheel housing
333 Airbag
In the steering wheel
334 Earthing point for the electronic unit and test connector
Adjacent to the electronic unit
335 2-pole orange connector
The pins are short-circuited when the connector is separated
336 Slip-ring contact
In the steering wheel
400 Redundant earth for the airbag
On the left-hand wheel housing, accessible from the interior
Operation
The steering wheel pads of cars equipped with the Airbag system are marked "SRS" (Supplemental Restraint System).
The system consists of two front sensors, an electronic unit, a safety sensor and a steering wheel pad containing a gas generator and an airbag.
The system will be activated when at least one of the two front sensors and the safety sensor are subjected to a retardation force equivalent to a frontal collision at around 20 km/h (12 mph).
The supply to the system is taken from distribution terminal +15 when the ignition switch is in the start or drive position, and from the +50 supply when the ignition switch is in the start position.
Front sensor
The front sensor consists of a contact roller which is held in the rest position by a spring. When the roller is subjected to a force of at least 16 g, it will roll forward and close the circuit. The front sensor must therefore be mounted facing the right way.
Electronic unit
The electronic unit contains the safety sensor, a capacitor pack, and the firing and monitoring circuits. The electronic unit must also be mounted facing the right way.
Steering wheel pad (Airbag module)
The gas generator and the airbag are located in the steering wheel pad.
Gas generator
The gas generator consists of an aluminium case with a centre compartment and two annular compartments.
The centre compartment includes an electric detonator and an explosive charge, and is in communication with the inner annular compartment.
SRS warning lamp
The SRS warning lamp is located in the combined instrument.
The SRS lamp will light up for around 6 seconds when the ignition key is turned to the start or drive position, and will then go out if there are no faults in the system.
Supply
When the ignition switch is turned to the start or drive position, the supply (+15) is taken across pin 3 in connector 98 to pin 18 in electronic unit 331, thus charging the capacitor pack. The capacitor pack serves as a power supply reserve in the event of loss of supply at the instant of collision. At the same time, SRS lamp 47T in the combined instrument will be energized from the +54 supply, across fuse 7.
SRS lamp 47T will be earthed across pin 7 in connector 98, and pin 20 in electronic unit 331, and will light up.
When the ignition switch is turned to the start position, pin 16 in electronic unit 331 will be energized (+50), which will start the measurement cycle, etc. in the diagnostic unit.
Activation of the airbag
In a collision, the airbag and the seat-belt tensioners will be activated if the front sensors and the safety sensor in the electronic unit sense a retardation of at least 16 g at the front sensor and at least 2 g at the safety sensor.
The contacts in each sensor will then close and the capacitor pack in the electronic unit will discharge, applying a current pulse to the electric detonators in the airbag.
Earthing
Do not connect earth cables of other systems to the mounting screws of the front sensors and the electronic unit, since this may cause disturbances in the system and fault indications from the electronic unit.
Fault codes
If a fault should occur in the system, the SRS lamp will flash when the ignition switch is in the drive position. The far It codes stored in the memory of the system can be read by connecting the SRS tester to test connector 330.