JLG 800A_AJ Service Manual - Manual (Page 279)

SECTION 4 - BOOM & PLATFORM
3120858 – JLG Lift – 4-65
4.19 UMS TROUBLESHOOTING AND FAULT
MESSAGES - NON-ADE MACHINES
Tower Lift Down Permanently closed
2/2 FUNCTION LOCKED OUT - TOWER LIFT DOWN PER-
MANENTLY CLOSED
The control system shall illuminate lamps and sound the
alarm at startup for one second on and one second off. If
the control system detects the TOWER LIFT DOWN, it
shall report a fault. The TOWER LIFT DOWN function shall
be locked out and activate the ground boom malfunction
indicator lamp, upright tilted lamp and platform alarm con-
tinually until the condition is cleared.
Solution:
• Inspect switch and harness. Voltage (12V) should
only be present on J1-3 of the UMS module when
Tower Down switch is closed.
Backward Stability Concern Message
2/5 UMS SENSOR BACKWARD LIMIT REACHED
When the upright angle relative to the turntable is higher
than +2.5° (away from the work platform), tower lift down
shall be disallowed immediately. Tower Lift Down shall be
re-allowed when the upright angle relative to the turntable
is less than 2.0. If Tower Lift Down is disabled for more
than 1.5 seconds, the ground boom malfunction indicator
lamp, upright tilted lamp and platform alarm shall light/
sound continually and a fault shall be raised. These condi-
tions shall be latched along with Tower Lift Down until the
upright angle is less than 2.0 for 2 seconds and the
Tower Lift Down command is returned to neutral.
Solution:
• Inspect sensor mounting.
• Verify sensor calibration on level pad.
• Follow the corrective action listed on decal 1702265
located near the red knob of the machine.
• Inspect machine hydraulics. Refer to Holding Valve
Checks in Section 5 - Hydraulics.
Forward Stability Concern Message
2/5 UMS SENSOR FORWARD LIMIT REACHED
When the upright angle relative to the turntable is less
than –4.0° for longer than 1.5 seconds, the ground control
boom malfunction indicator lamp, the platform malfunc-
tion indicator lamp, and platform alarm will light/sound
continually and a fault will be raised. The light/alarm signal
will stop only when the upright angle reaches values
greater than –3.0° for 2 seconds.
Solution:
• Inspect sensor mounting.
• Verify sensor calibration on level pad.
• Tower lift down.
• Inspect machine hydraulics. Refer to Holding Valve
Checks in Section 5 - Hydraulics.
Auto Detection Input Low Message
2/5 AUTO DETECTION INPUT LOW
If the UMS detects a valid ground module software version
but digital input 2 is not tied high the UMS module shall
report a fault.
Solution:
• Inspect wire harness, there should be 12 volts going
into pin J1-5 (black connector) of UMS module.
UMS Sensor Communications lost
6/6 UMS SENSOR COMMUNICATIONS LOST
If the UMS detects a valid ground module software version
but digital input 2 is not tied high the UMS module shall
report a fault.
Solution:
• Inspect wire harness; CANbus communications are on
pins J2-9 & J2-10 (gray connector) of the UMS module.
• Using access level 1 of the UMS module, under “DIAG-
NOSTICS” CAN, RX/SEC and TX/SEC should be val-
ues greater than 0. Also “BUS OFF:” and “BUS ERR:”
should be 0 and “PASSIVE:” should be a low value.