Operating Strategies; Actuation Of Gear Changes; Locking Of Torque Converter (Lock-Up Function); Execution Of Driving Mode - Fiat Bravo Service Manual

Bravo-Brava
O P E R A T I N G S T R A T E G I E S

Actuation of gear changes

The change from one gear to the higher or lower gear depends on the accelerator pedal position, the ve-
hicle speed, the engine's characteristic parameters and the driving mode selected by the driver.
The control module sends an ON/OFF signal to the solenoids S1 and S2.
They consent or prevent the oil from reaching the brakes and clutches necessary for obtaining the dif-
ferent transmission ratios, changing their condition from ON to OFF and vice versa as s h o w n in the table
below.
Gear Solenoid S1
1st ON
2nd ON
3rd OFF
4th OFF

Locking of torque converter (lock-up function)

The engagement of the lock-up clutch for locking the torque converter depends on the gear engaged,
the accelerator pedal position, the vehicle speed and the selected driving mode.
The control module sends a duty-cycle signal to the lock-up control solenoid SL, w h i c h discharges the
oil pressure in the chamber on the flywheel side, causing the clutch to be engaged and the converter to
be locked.
The control module has t w o specific programs for locking the torque converter memorized for the NOR-
M A L and SPORT driving strategies, while for the ICE strategy the torque converter is not locked.
These programs are described on the following pages in the section concerning the driving modes.
The converter is not locked under the following conditions:
1. w h e n the control system receives a fault signal from one of the components and executes the recov-
ery strategy;
2. w h e n the brake pedal is pressed and the gearbox input speed is below a certain value;
3. w h e n the throttle valve is closed (accelerator pedal not pressed) and the vehicle speed is below 125
k m / h with the selector lever on position D;
4. w h e n the engine coolant temperature is below 75°C.
During the 3rd-4th gear change, w i t h lock-up clutch engaged, the control module sends to the solenoid
SL a signal with variable duty cycle, so as to temporarily disengage the lock-up clutch, to improve the
quality of the gear change.

Execution of driving mode

The control module is designed to control the operation of the automatic transmission in accordance
w i t h three different driving modes.
The three driving modes allow the driver to select the different capabilities of the automatic transmission
in accordance w i t h the momentary requirements of use:
- N O R M A L to obtain the maximum driving comfort, while minimizing fuel consumption;
- SPORT to obtain the maximum performance of the vehicle;
- ICE to increase driving safety under slippery conditions.
Copyright Fiat Auto
ft** Auto transmission and differential
Solenoid S2
OFF
ON
ON
OFF
Components and operation
The 3rd-4th gear change is prevented w h e n
the engine coolant temperature is below
75°C.
The control module has specific gear change
programs memorized for each driving mode
( N O R M A L , SPORT, ICE), w h i c h w i l l be de-
scribed on the following pages in the section
relating to the driving modes.
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