Troubleshooting - JLG 1850SJ Service And Maintenance Manual

SECTION 6 - JLG CONTROL SYSTEM

Troubleshooting

The following tables are furnished to provide possible resolu-
tions for common difficulties. Difficulties are classified as Gen-
eral, Calibration, Measurement Performance, and Host System
Functionality.
Difficulty
Empty Platform Weight (DIAGNOSTICS, PLAT-
FORM LOAD) is not within ±15lbs (±7kg) of
zero.
or
Platform Load readings (DIAGNOTICS, PLTLOAD)
are unstable by more than ±2lbs (±1kg) (with-
out the influence of vibration or wind).
or
There are large variations in Platform Load
(DIAGNOSTICS, PLTLOAD) based on the location
of the load. Tolerance to variations is 20lbs for
an evaluation using the technician's weight,
and +5% of Rated Load when using calibrated
weights.
The Visual and Audible Overload Warnings fail
to sound when platform is loaded beyond Rated
Load, or when simulated by unplugging the
Load Cell. Controls remain functional at Plat-
form and Ground Control positions.
The Ground Audible Warning fails to sound, but
the Platform Audible Warning sounds properly.
Controls remain functional at the Ground Con-
trol position during an overload, or when simu-
lated by unplugging the Load Cell. The Controls
at the Platform Control position are prevented
when using the engine, but not when using the
Auxiliary Power Unit.
6-106
Table 6-11. LSS Troubleshooting Chart
The LSS System is unable to properly measure the platform weight.
1. The Load Cell is not properly plugged into the LSS Harness. It is possible poor electrical contact is made.
2. Wiring leading to the Load Cell is damaged. Carefully inspect sensor wiring where it passes through cable clamps for signs of damage.
Inspect wiring where damage to the channel is apparent.
3. The Load Cell was not assembled properly during installation. Examine the sensor' s reading using the JLG Analyzer. Proceed to the DIAG-
NOSTICS, CELL, LOAD displays and determine if the readings are reasonable. It is often helpful to apply slight downward pressure above the
sensor and observe that its output increases (increasing force measurement; decreasing means the sensor is mounted upside-down).
4. The Load Cell is contaminated by debris or moisture. Examine the sensor's reading using the JLG Analyzer. Proceed to the DIAGNOSTICS,
CELL, LOAD displays and determine if the readings are reasonable and stable (not changing by more than ±2lbs (±1kg) (without the influ-
ence of vibration or wind). Lack of measurement stability is a key indication of contamination. Unplug the connector and inspect for dirt or
moisture. Look carefully into the female connector on the sensor's cordset for evidence of contamination. Debris should be brushed away
with a soft bristle brush (do not introduce any cleaners as they will leave conductive residue). Moisture should be allowed to evaporate or
accelerated with a heat-gun (use low heat and be carefully to not melt connector materials). Moisture intrusion into the molded portion of
the connector (capillary action into the wire bundle) or the Shear Beam Load Cell itself will require replacement of the sensor.
5. The Load Cell has been mechanically damaged. If the Load Cell is physically deformed or has damage to the cover it should be replaced
immediately. It is also possible to have invisible mechanical damage resulting from an extreme overload (>6000lbs [>2722kg]).
The Control System is failing to regard the overload signal from the LSS System, or the signal is shorted.
1. The Load Sensing System must be enabled within the Control System. Plug the JLG Analyzer into the Control System, enter the Access
Level 1 password (33271), and examine the MACHINE SETUP, LOAD sub-menu. The selection "2=CUTOUT PLT" should be displayed (plat-
form controls prevented during overload, ground controls remain operational). In country- or customer-specific circumstance, the selec-
tion "3=CUTOUT ALL" is used (platform and ground controls prevented during overload).
The Ground Alarm is missing or improperly installed. Verify that the device is mounted. Verify wiring from the Main Terminal Box and
Ground Module.
The JLG Control System is configured to prevent platform controls only in the event of overload. Alternately, the Host Control System can be
configured to prevent ground and platform controls for country- or customer-specific circumstances.
Using the JLG Analyzer, enter the Access Level 1 password (33271). Proceed to the MACHINE SETUP, LOAD sub-menu. Set this parameter to
"2=CUTOUT PLT" to prevent platform controls in the event of overload. Set this parameter to "3=CUTOUT ALL" to prevent platform and
ground controls in the event of overload.
Possible Resolution
3121619