JLG M600 Service Manual - Manual (Page 65)

SECTION 3 - CHASSIS & TURNTABLE
3121813 – JLG Lift – 3-27
Speed Sensor Installation Verification
The motor controller averages the readings from the right
and left speed sensors and therefore, it can be difficult to
detect if the speed sensors are adjusted properly. When
the positrac keeps coming in and out while on level sur-
faces, this is a sure indication that one of the speed sen-
sors is not adjusted properly.
The worse case condition of speed sensor misadjustment
occurs when both sensors are installed in a manner that
allows them to indicate the exact opposite direction that
the machine is traveling. This situation causes the control-
ler to believe that the machine is rolling in opposite direc-
tion than that selected by the operator. The controllers
reaction to this situation is to put more power into the
drive motors to attempt to overcome the fact that it
believes the machine is rolling backwards. This presents
itself as uncontrolled movement in the direction selected
by the operator until the controller recognizes that it is
placing maximum power in the motors and the controller
and the speed sensors are still reporting movement in the
opposite direction. The controller responds by shutting
down drive and reporting flash code 5/5- Vehicle Runaway
Check Speed Encoders.
If either speed sensor is disconnected or faulty, the con-
troller will recognize this condition and immediately report
flash code 5/5 - Left or Right speed Encoder Faulty.
Verification w/ Analyzer Procedure
Below is a procedure using the Analyzer that will verify
that the speed sensors are installed correctly.
THIS PROCEDURE REQUIRES A LARGE SPACE CLEAR OF
OBSTRUCTIONS. THE OPERATOR SHOULD BE FAMILIAR WITH
JLG EQUIPMENT AND BE PREPARED TO USE THE FOOTSWITCH
TO STOP THE MACHINE. READ AND UNDERSTAND THIS ENTIRE
PROCEDURE PRIOR TO BEGINNING.
1. Before beginning this procedure, insure that there is
at least 10 ft (3m)in front and back of machine. Be
sure that all other personnel stand clear of the
machine during this procedure.
2. Unplug the left speed sensor from the posi-trac tilt
module.
3. Power up the machine in platform mode and plug in
the Analyzer in the platform.
4. Use the right and left cursor keys on the analyzer to
highlight "DIAGNOSTICS" and press enter.
5. Use the right and left cursor keys on the analyzer to
highlight "DRIVE" and press enter.