69 - 9
4WD
The machine driver has 2 inputs which are used to influence
the state of the 4WD solenoid output. These features
interact as follows;
Firstly there is a Direct 4WD input which is, in general,
connected to the machine footbrake switch (which in turn
controls the brake lights). Whenever this signal is present the
4WD Solenoid output is energised.
The second input is Indirect 4WD which is usually derived
from a command from a console mounted '4WD selector'
switch. (However, this switch arrangement may change
between machines.) If the transmission speed is too high
then the ECU will over-ride this signal and automatically
disengage the 4WD.
Misc. Inputs
These inputs are derived from the remaining driver controls.
A brief summary follows but refer to the Fault Finding Guide
for full details.
Handbrake Switch: Signal derived from the Parkbrake
switch. Used to hold the transmission in Neutral if the
parkbrake is applied.
Dump Switch (or Transmission Disconnect): Signal usually
derived from a momentary switch fitted to a loader lever.
Temporarily selects Neutral when pressed (usually to divert
engine power to hydraulics).
Throttle Switch: Dedicated switch fitted to the machines'
accelerator pedal. Used to interact with the Automatic Mode
of gear-shifting.
Pressure Switch: Signal is derived from the transmission
mounted Low Oil Pressure Switch.
Kickdown Switch: Another momentary button (mounted on
the cab floor) used to temporarily select the next lowest
gear.
Misc. Outputs
These are the additional ECU outputs, generally used to
control cab instrumentation like the low Oil Pressure Lamp
and Driver Indicator (lamp and buzzer where fitted).
13. General Information
For all enquiries about the ShiftMaster Diagnostics tool
please follow your normal channels of enquiry. This ensures
that useful information can filter through to JCB Service
personnel at all levels.
Section F Transmission
9803/3280
Section F
69 - 9
Issue 1
Service Procedures
Powershift Gearbox - 6 speed
ShiftMaster Diagnostics - User Guide
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