JLG 20VP (3120728) Service Manual - Manual (Page 86)

SECTION 3 - TROUBLESHOOTING
3-26 – JLG Lift – 3120728
Will Only Drive A Short Distance
Overview Of Procedure
The following procedure will eliminate any problems found in the power circuit to the MC-1 controller box and also any
objectionable environmental conditions.
Check For These Obvious Conditions First:
• Is Battery Voltage 24 Volts? (Fully Charge Batteries)
Table 3-16. Only Drives A Short Distance
STEP ACTION SPEC YES NO
1. Is platform controller staying powered up when machine stops driv-
ing?
— Go to Step 2
Check the E-Stop
& Key Switch
Circuit
(Table 3-17)
2. Check the voltage out of the X101 connector, pin 5, to the power
relay pin 86. Check continuity at pin 85.
24 Volts Go to Step 3
Repair or Replace
Wires, or Problem
with MC-1 Box
3. Check the voltage from pin 87 on the power relay to the main con-
tactor. (Main contactor should be closed at this point)
24 Volts Go to Step 4
Repair or Replace
Wires or Relay
4. Check the voltage on the Yel/Red, 2-5 wire on the X101 connector,
pin A1, from the main contactor.
24 Volts Go to Step 5
Repair or Replace
Wires or Main
Contactor
5. What type of surface is machine being operated on? Is surface soft,
unstable or up a steep grade?
—
Machine will not
perform well on a
soft or unstable
surface, if motor
draw is over 70
amps, controller
will shut the
machine down.
( 7 LED Code)
Go to Step 6
6. Are brakes releasing when trying to drive?
— Go to Step 7
Repair/Replace
or Adjust Drive
Brakes
(See Procedure in
Service Manual)
7. Is drive system running free? No noise or dragging.
— Go to Step 8
Repair/Replace
or Adjust Drive
System
(See Procedure in
Service Manual)
8. Is machine being operated in an environment with high static
charge?
—
Machine may be
building static
charge in the MC-
1 controller,
which will make
the drive system
shut down.
—