Electronic Control Unit - Fiat Brava Service Manual

Electrical equipment Bravo-Brava
Air bag
ELECTRONIC CONTROL UNIT
The electronic control unit (page 95 reference 1) is located in the car console housing and fastened
rigidly to the floor pan.
It is fitted with a 30 pin connector (page 95 reference 2). Nine pins are used for connection to the elec­
trical system. It is supplied with 12V when the ignition key is turned to MARCIA, but is able to continue
working for about 100 ms after the power is cut off, if this should occur as the result of a crash.
This is possible due to the presence of a buffer condenser inside the electronic unit. This accumulates
electrical energy to allow the electronic control unit to work normally and to generate the ignition signal
required to set off the explosive capsule.
Air-bag operation is therefore ensured even if impact causes system power to be cut off (e.g. damaged
or broken battery, broken supply leads etc.).
The control unit must be positioned with arrow (3) facing in the vehicle's direction of motion.
This position must be STRICTLY OBSERVED, because it determines the direction in which the deceler­
ation signal is detected and is used to assess impact status and thus cause the air bag to operate.
The control unit contains an accelerometric sensor. This produces a signal which is processed by a mi­
croprocessor to reveal the severity of impact. The microprocessor then determines whether to set off the
pretensioners and air bags.
94 II-98 - Supersedes previous version Publication no. 506.670/14