Check valve

Pressure Return Neutral

EVF EV 3(OFF)

EV 4ON

EV 5ON

EV 1

engagement ONEV 2

engagement ON

GEAR 4-5 POT

Engagements/selection

pump electric motor Electric pump

The electric pump brings the oil from the hydraulic reservoir to the operational pressure for the power unit.

The pump is driven by an electric DC motor and is managed by an ON/OFF control strategy (the pump does not run continuously). The pump is activated when hydraulic pressure drops below 40 bar and is switched off when the pressure reaches 50 bar.

When the driver's side door is opened and the ignition key is not inserted, the transmission control module (NCR) runs the pump briefly to build up hydraulic pressure before starting the engine.

In case of replacement of the electric pump, the pump must

be replaced together with its activation relay!

Pressure accumulator

The system is equipped with a piston type pressure accumulator located on top of the gearbox. The function of this device is to accumulate hydraulic pressure during the electric pump running time and deliver high pressure oil to the power unit when the pump is stopped.

Sofast 4:

For the Sofast 4 system (GranTurismo S and GranTurismo MC Stradale) with Superfast shift shiftshiftshift strategy, a higher operating pressure is obtained when the Superfast shift shiftshiftshift mode is active (range 50 - 70 bar). Therefore, a new, more powerful electric pump is used. Further, an air conveyor is installed to provide fresh air to the pump for heat removal.

The temperature of the electric pump motor is monitored by the NCR by means of a mathematical model. In base of certain temperature thresholds, specific recovery strategies can be activated to prevent overheating of the pump.

Solenoid valves internal leakage

Leakage past the spool of the control valve, which is estimated by the NCR and can be read out by the diagnostic system, constitutes a valuable diagnostic aid in the event of an electrohydraulic system fault. The value shown is periodically acquired by the NCR in a self-learning procedure.

Solenoid valve internal leakage in excess of 30 cc/min, combined with problems of engagement and/or selection, offers an excellent point of reference to understand the nature of the problem. In this case the solenoid valve must be renewed.

In the case of hydraulic problems use the following procedure in order to isolate the offending component:

Key ON, Engine Off: the interval time between two pump activations must be no less than 2 minutes. This makes it possible to check the solenoid valves accumulator -electric pump assy.

Key On, Engine running: the interval time between two pump activations must be no less than 60 seconds. This makes it possible to check the clutch solenoid valve and, by acquiring the pump restart times, the condition of the accumulator.

The conditions of the electric pump can be assessed by acquisition of its activation time: an activation ramp with an increasingly gradual slope and activation time in time: an activation ramp with an increasingly gradual slope and activation time in excess of 5 seconds are clear symptoms of deterioration of the pump.

Up / down paddles

Selection of gear engagement by means of steering wheel paddles

The NCR checks the activation status of the paddles by means of voltage values generated by activation of the gearshift paddles.

Clutch Actuator

The clutch actuator is responsible for activating the clutch thrust bearing; the actuator is composed of a hydraulically operated circular ring. Attention must be payed to the A contactless type sensor is used to measure in real time the position of the clutch release bearing. This sensor uses LVDT (Linear Variable Differential Transformer) technology. The movement of a magnet, fitted on the release bearing, will affect the voltage induced in the coils integrated in the sensor element.

Note: failure of the clutch position sensor may lead non-starting of the engine.

Clutch position sensor

composed of a hydraulically operated circular ring. Attention must be payed to the correct direction of installation of the position sensor magnet with reference to the clutch thrust bearing position.

Pressure plate

Gearbox side Magnet

(facing gearbox side)

Clutch pressure plate in rest position:

Clutch pressure plate in working position:

Measuring range: 0 - 80 bar Response voltage: 0.5 - 4.5V

Longitudinal acceleration sensor (Sofast III)

Hydraulic pressure sensor on clutch housing (Sofast III onward)

An analogue pressure sensor measures the hydraulic pressure in the clutch actuator, which is in direct relation to the application force of the diaphragm spring. By this way the exact clutch characteristic can be identified. This component is installed starting from sofast III.

A longitudinal acceleration sensor was introduced on the Sofast III system to allow to calculate the road gradient (flat surface, uphill, downhill). This information is used by the NCR to adapt the clutch activation during driving away and the gearshift strategy in automatic driving mode in base of the road gradient.

Starting from assembly 24275, the sensor has been dropped and longitudinal acceleration ionformation is received from the ABS / ESP system (NFR) over the C-CAN line.

The rotation speed of the gearbox primary shaft is monitored by a magnetic induction type speed sensor located on the right-hand side of the gearbox.

Gearbox input shaft speed sensor