jcb 3CX Service Manual

40 - 5 Section F Transmission 9803/3280
Section F
40 - 5
Issue 2*
Fault Finding
Powershift Gearbox
Chart D - (6 speed gearbox only) ShiftMaster fails to function normally - fails to autoshift - shifts at incorrect road speed.
Note: 4th, 5th and 6th gears utilise clutches used for 1st, 2nd and 3rd gears. If 4th, 5th or
6th gears fail to engage, check that the lower 3 gears function correctly before investigating
a possible ShiftMaster fault. See Fault Finding Chart C.
The simplest and best way to fault find the 6 speed gearbox electrical system, (including the
ECU) is by using ShiftMaster Diagnostics software and a laptop PC. See Diagnostics User
Guide. This diagnostics system enables the engineer to quickly identify faults with specific
electrical circuits or devices. The devices electrical connections, locations and wire
identifications are given in Electrical Connections - Powershift Gearbox - 6 Speed. See
also Section C - Harness Data.
‘Limp Modes’
When applicable the ShiftMaster ECU provides restricted or modified gearbox operation if
faults are detected by the ECU. Typical ‘Limp Mode’ forms of operation are:
YES
NO
YES
YES
START
Is the speed sensor operating?
See Service Procedures - Powershift
Gearbox, Speed Sensor.
Renew sensor or repair wiring as
applicable.
Clean connectors and fit securely.
Use ShiftMaster Diagnostics software
to check ECU inputs and outputs. See
Service Procedures, Powershift
Gearbox, Diagnostics User Guide.
Is the gearbox ECU connected
correctly?
Renew the ECU.
See Service Procedures,
Powershift Gearbox, Electronic
Control Unit.
NO
NO
Are the gear selection column
switches, kickdown and throttle
switches working correctly?
Renew the switch or repair wiring as
applicable.
A396310
Limp Mode 1 Possible Reason
Machine autoshifts at different road Internal ‘Setup Data’ ECU fault.
speeds than normal. If on power-up the ECU detects an internal fault
2 Beeps at power-up. with its ‘Setup Data’ it will revert to use of a
default set of values.
Limp Mode 2
Machine remains in neutral at all times. Error with ECU ‘Application Software’.
1 Beep at power-up. If on power-up the ECU detects an internal fault
with its ‘core operating software’ it will prevent
operation of the gearbox.
Limp Mode 3
Only 1st, 2nd, and 3rd gears available. Error reading transmission speed.
Machine will not autoshift. If the ECU does not detect any input from the
speed sensor it will prevent selection of any gear
above 3rd.
Limp Mode 4
Machine holds a gear. Error reading transmission speed.
Repeating beeps until ECU power is If the ECU detects an error with the speed
reset. sensor whilst operating it prevents autoshifting.
*
*
*
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Note: On power-up the ECU will normally sound 3 beeps. These beeps can be masked by
other audible warnings on start up.
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jcb 3CX Specifications

General

Brand	jcb
Model	3CX
Category	Compact Loader
Language	English