3.3 POWER LIFT CONTROL UNIT 3. INTRODUCTION TO THE ELECTRONIC SYSTEM OF THE TRACTOR 3.3.2 ASM SYSTEM The lift control unit also governs the ASM system which, when activated by the operator, manages the engagement and disengagement of the four wheel drive clutch and differential lock mechanism automatically. The parameters used to determine exclusion of the differential lock and disengagement of the four-wheel drive are: - wheel speed; - steering angle; - type of braking action (one or two pedals). The command which activates the system, and the signals from the brake pedal, wheel speed and steering angle sensors are all routed directly to the control unit.
The control unit processes the data and, according to the status of the system and the parameter settings, activates or de- activates the solenoid valves controlling engagement of four-wheel drive and of the differential locks. The hydraulic lift control unit warns the operator of any malfunction in monitored components by way of a red Led (lift trans- port lock indicator) located on the lift control console. Faults are indicated using a system of coded flash sequences which, depending on how the control unit has been con- figured, will either specify the precise nature of the fault (extended alarm) or simply identify the device affected (standard alarm).
Also, and likewise depending on the configuration, the unit can display only the alarm with the lowest code (rotation of alarms deactivated), or it can display all the active alarms (rotation of alarms activated). The ART shows the 10 most recent alarms generated, and if a further alarm is triggered, the first of the ten will be eliminated. To verify, using the ART, whether or not an alarm detected is “active”, the technician must cancel all the alarms, turn the starter key to the “ O ” (OFF) position, then make a fresh connection to the control unit.
ST2 JX1 9 JX2 JX2 8 20 4 5 JX1 7 7.5A F34 7.5A F34 +15 +15 6 X35 X82 1 4 2 3 3 1 4 2 1 EV DF 2 1 X32 RL9 1 2 3 4 5 4 1 2 20A F11 4 5 1 2 +15 D0017290 3 1 - Four wheel drive (4WD) clutch solenoid valve 2 - Differential lock solenoid valve 3 - Steering angle sensor 4 - Right brake pedal switch 5 - Left brake pedal switch 6 - ASM switch 7 - Differential lock switch 8 - 4WD switch 9 - Instrument panel 20-17 1 14 2 8 9 3 0 1 1 10 1620 11 2 1 0 1 6 6 0 1 2 8 6 5 2 1 4 5 3 2 3 1 4 5 5 4 1 2 2 1