JLG sky trak mmv Service Manual page 636

Electrical System
Boom Sensor (Proximity Switch)
The boom sensor (1 or 8) is a proximity switch located on
the rear of the vehicle frame at the boom pivot point.
When energized, the sensor creates a magnetic field and
detects the presence of the boom (2), as the boom is
raised or lowered past the sensor. Depending on condi-
tions (including boom raised above or below 40°, parking
or service brakes ON or OFF, Stabil-TRAK engaged or
not, etc.), the boom sensor and its electrical circuitry will
either allow or disallow certain hydraulic functions. When
the boom is below 40°, a red L.E.D. light (9) is illuminated
on the boom sensor. The L.E.D. light will turn off when the
boom is above 40°.
5
6
2
1
4
Side View
13
11
10.156
Top View
3
7
MT0430
10
8
12
9
MT3120
Boom Sensor Replacement and Adjustment
The boom sensor (1) is removed by disconnecting the
wire lead (3) from the wiring harness connector, removing
the sensor mounting nut (4), and removing the sensor
from the mounting bracket (5) on the vehicle.
IMPORTANT: The boom sensor mounts into a slotted
mounting bracket. The sensor must be positioned in the
slot so the Stabil-TRAK dash light will illuminate (as seen
from the operator's position) when the boom is raised
and reaches exactly 40°.
To install and adjust a boom sensor:
1. Place the sensor into the mounting bracket (5).
Thread the sensor mounting nut (4) onto the boom
sensor.
2. Adjust the sensor mounting nuts (4 and 7) to achieve
a 1/8"-3/16" (3,17-4,76 mm) gap (6) between the
sensor (1) and the boom (2). Tighten the inner
sensor mounting nut (4) to 36 lb/in (4 Nm).
3. Connect the boom sensor to the wiring harness
lead (3).
4. Operate the boom through its full range of motion;
the boom must NEVER touch the sensor.
5. As the boom is raised, ensure that the Stabil-TRAK
dash light illuminates when the boom reaches the
40° (as seen from the operator's position) raised
position. If the light does not illuminate at the 40°
position, loosen the inner sensor mounting nut (4)
and adjust boom sensor position up (10) or
down (11) within the machined slot (13) of the
weldment (12) until the Stabil-TRAK dash panel light
illuminates. Tighten the inner sensor mounting
nut (4) to 36 lb/in (4 Nm).
Note: The boom sensor has a L.E.D. (9) that is illumi-
nated when the boom is below 40°.
6. Check the function of the Stabil-TRAK system as
described in Section 11, Stabil-TRAK™ System .
Model MMV Rev. 12-04