BRAKES
FIAT PUNTO TRAINING OUTLINE
Fiat Auto S.p.A.
After Sales Training
6.5 E.S.P.
The E.S.P. (Electronic Stability Program) is an active safety system for controlling the vehicle
during dynamic manoeuvres. It comes into operation in emergency situations and has been
designed to correct the path of the vehicle in case of sudden manoeuvres (which are often
unintentional), thus enhancing active safety, especially on slippery road surfaces. In fact, the
E.S.P. promptly responds both to oversteering and understeering, and is set to resume the
vehicle’s stability condition while allowing the driver to fully control the vehicle.
The system continuously monitors the vehicle motion conditions (side acceleration,
longitudinal and angular speed, road grip) and the driver’s setting (steering wheel angle,
accelerator pedal). The system corrects the vehicle motion when it “feels” that the vehicle is
about to reach a condition of instability (sideslip, understeering, oversteering, etc.): in this
case, it acts on the deflecting torque control and applies a proper braking torque distributed to
each of the four wheels.
Direction is controlled by taking advantage from the tyre’s longitudinal grip: the different
braking action between the two vehicle sides generates a rectifying (yawing) torque that
stabilizes the vehicle.
The ESP function is managed by the ABS control unit which monitors, by processing the
values of the quantities acquired from the various sensors (side acceleration sensor, yaw
sensor, steering angle sensor, wheel revs sensors and pressure sensors) through algorithms
implemented in the software, the dynamic control parameters (wheel slip, axle drift, trim angle)
and interprets the mistakes (if any) made by the driver, thus taking adequate actions in order
to resume the vehicle’s stability condition.
The system is made up of the following components:
4 wheel speed sensors fitted into special seats on the front and rear pillars;
1 side acceleration and yaw sensor incorporated into one single device fitted onto the central
tunnel;
1 electro-hydraulic unit fitted onto the special support in the engine compartment;
gb Fiat Grande Punto OK
354 / 532
© 2005 Fiat Auto S.p.A. – All rights reserved.
1 switch on the brake pedal;