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Dan, Technician
Category: Industrial Equipment
Satisfied Customers: 5168
Experience:  17+ yrs. shop and field experience with all major brands of heavy equipment and trucks - 1995 WyoTech graduate.
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Im working on jlg 4394rt scissor lift. i can not get the

Customer Question

im working on jlg 4394rt scissor lift. i can not get the handheld analyser to calibrate the tilt sensor
Submitted: 1 year ago.
Category: Industrial Equipment
Expert:  Dan replied 1 year ago.

Hi my name is***** is the serial number of your lift?

Customer: replied 1 year ago.
hy dan my serial number is ***** follows###-##-####
Expert:  Dan replied 1 year ago.

Tilt Sensor Calibration:

1. Drive the machine onto

a measured level surface

(±0.5° for both x and y axis).

2. Using the Analyzer, go to MENU: CALIBRATION;

TILT SENSOR. Press Enter.


play. Press Enter again to calibrate.

3. Both axis’ raw angles need to be within


5.0°, other-

wise the machine is too unlevel and the software will

prohibit calibration. Should this occur, attempt to

dissect the three areas of

error to find the primary


a. Machine mounting and/or grade:

With a digital level, measure the top of the

Ground Control box for levelness. If unable to

get a good reading, check the box’s mounting

surface for levelness.

b. Tilt sensor mounting on machine or wedged

crooked in control box:

If the machine mounting/grade appears accept-

able, open the Ground Control box carefully.

Observe whether the tilt sensor is properly


c. Tilt sensor has developed an offset shift:

Remove the tilt sensor from the Ground Control

box, but keep both the tilt sensor and Ground

Control box electrically

connected. Level one

axis of the tilt sensor and observe the raw read-

ing (should be within ±2.0°). Do the same for the

other axis. If either axis

is greater than ±2.0°,

replace the tilt sensor.

Some possible reasons that the tilt sensor will not cali-

brate are:

a. The surface the machine is sitting on is off level

by a few degrees (flat doesn’t imply level; park-

ing lots are often not level).

b. The tilt sensor has failed one or both of the

channels (X axis and Y axis).

c. Tilt sensor has moisture intrusion that has

shifted its output.

d. Water and/or corrosion in the box has corrupted

electrical connections or

caused a tilt sensor or

ground control board

failure (observe any

cracks in the box).

e. The Ground Control Box, as mounted on the

machine, does not allow the tilt sensor to be


For the following troubleshooting steps, a bubble level

(smaller is better) will be

needed and the machine must

be on a level surface:

1. On the Analyzer, go to Diagnostics/System and read

the tilt angle. If either angle reports +20.0°, there is

an electrical/electronic failure (tilt sensor, control

board, electrical connections).

a. Open the Ground Control Box.

b. Disconnect the sensor and clean any corrosion

off of the tilt sensor and control board connec-


c. Reassemble and test. If fault persists, replace tilt


2. If the Analyzer displays angles other than +20.0°,

attempt to calibrate. If machine will not calibrate,

note the reason displayed on Analyzer:

a. SENSOR FAILURE – tilt sensor internal fre-

quency is out of range (replace sensor).

b. NOT LEVEL - tilt sensor has either developed an

offset or it is too unlevel as mounted on the


Tilt sensor wiring ( Sensor is located and mounted inside the control box to the top by 4 screws):

Wire Color-Function-Connector Pin

Red- VCC- 1

Green- PWMX- 2

White- PWMY- 3

Black- Ground- 4

Check for levelness of the sensor and control box as described, inspect/test harness and ground, or replace faulty sensor and relevel the sensor. Let me know

Customer: replied 1 year ago.
i went through the whole jlg service manual . i even unscrewed the box with tilt sensor and had my x and y at 0 so it was perfectly level . when i press enter on calibration for tilt sensor nothing happens and no fault codes are present . my lift is not getting to full height from the platform but it is from the ground control .i have had this problem before but after i calibrated the tilt sensor all was ok
Expert:  Dan replied 1 year ago.

Thanks for the info. If it will not even attempt to calibrate and no error messages it sounds more like a software issue with the controller if the tilt sensor is good.

Expert:  Dan replied 1 year ago.

Check to see if your JLG dealer can bench test the existing controller or reflash the software. Also try disconnecting the battery for 10-15 minutes to see if possibly the system may reset. Let me know

Customer: replied 1 year ago.
ill try the batterie disconect first and ill let you know what the results are
Expert:  Dan replied 1 year ago.

Sounds good. Pleasure to help.

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