3.2 TRANSMISSION CONTROL UNIT 3. INTRODUCTION TO THE ELECTRONIC SYSTEM OF THE TRACTOR 3.2 TRANSMISSION CONTROL UNIT The function of the transmission control unit is to supervise the correct operation of the transmission; it receives com- mands from the operator by way of the the shuttle lever, the range selection buttons and the clutch pedal, and, according to the signals returned by the engine speed and torque sensors, will shift between the ranges selected with the controls by piloting the operation of the 8 solenoid valves of the clutch actuators.
Connected to the control unit is a display that provides the operator with information on the current status of the trans- mission (direction of movement, range selected, etc.) and indicates any alarms detected by way of alphanumeric codes. Connecting the portable computer with the EDS software installed, the technician can display the alarms affecting the transmission. The alarms management function of the transmission control unit is based on two classes of alarms, defined active and passive.
The EDS program displays all alarms in two windows, showing information that includes the number of the detected alarm, its status (active or passive), the number of recurrences and the hours operation clocked by the transmission when the alarm first occurred. 1 E.C.U.
(PS) 15 3.9 Ohm 3.9 Ohm 3.9 Ohm RV FW N 14 +12V 13 F35 7.5A F16 3A 12 +15 +15 X12 F E Y4 11 10 9 8 7 6 5 2 3 4 D0023010 1 - Transmission ECU 2 - Gearshift lever 3 - Diagnostics connector 4 - Speed sensor for odometer 5 - Proportional solenoid valve coil 6 - Engine speed sensor 7 - Gearbox output shaft speed sensor 8 - Transmission speed sensor 9 - Transmission oil temperature sensor 10 - Engine oil low pressure switch 11 - Gearshift solenoid valves 12 - Clutch pedal position sensor 13 - Clutch pedal depressed proximity sensor 14 - Transmission display 15 - Shuttle control lever 20-15 3 20 30 1 2 11 8 573 2 55 29 5 14 39 15 16 3 40 17 21 45 36 13 56 62 4 44 24 37 38 67 22 68 2 3 M 5 M 6 g 2 1 3 2 1 N ls 2 8 2 3 3 2 1 fN lse 3 2 1 f N 2 1