JLG 20VP (3120849) Service Manual User Manual
Page 84
SECTION 3 - TROUBLESHOOTING
3-28
– JLG Lift –
3120849
14.
Check the Black to ground on the pump contactor.
Ground
Go to Step 15
Tighten/Repair
Connection
POWER RELAY CIRCUIT
15.
Check the Yel/Red, 2-4 wire, #87 on the Power Relay to the main
contactor, and to diode at E-Stop for 24 volts.
Note: Power will stop at diode, silver line should be away from the E-
Stop.
24 volts
Go to Step 16
Tighten/Repair
Connection
16.
Check the Yel/Red, 2-2 wire, #30 on the Power Relay to the E-stop
and to the MC-1 box, X101 connector pin 3, for 24 volts.
24 volts
Go to Step 17
Tighten/Repair
Connection
17.
Check the Black, #85 pin on the Power Relay for connection to
ground at pump contactor.
Ground
Go to Step
Tighten/Repair
Connection
18.
Check the Yel/Red, 2-3 wire, #86 on the Power Relay to the MC-1
box, X101 connector pin 5, for 24 volts when the platform control is
powered up.
—
Go to Step
Tighten/Repair
Connection
Table 3-22. Pump Valves Circuit
• Battery voltage 24 volts. (Fully charge batteries)
• Set key switch to Platform and set the Emergency Stop Button to the RESET position.
• Down Valve should be normal (closed).
• Dump Valve (up) should be normal (open).
• If machine will not lift and hydraulic oil is visible flowing in the hydraulic tank, the dump valve is stuck open.
STEP
ACTION
SPEC
YES
NO
LIFT UP - (CONDITIONS WHEN PUMP MOTOR IS RUNNING)
1.
Pump Contactor Coil:
Yel/Red, 2-6 wire - 24 volts
Tan, 55-1 wire - Ground
—
—
—
2.
Lift Up Valve Coil: Yel/Red, 2-6 wire - 24 volts
Tan, 3-1 wire - Ground
—
—
—
LIFT UP - (CHECK WHEN PUMP MOTOR IS NOT RUNNING)
3.
Pump Contactor Coil:
Yel/Red, 2-6 wire - 24 volts
Tan, 55-1 wire - 24 volts
—
—
—
4.
Lift Up Valve Coil: Yel/Red, 2-6 wire - 24 volts
Tan, 3-1 wire - 24 volts
—
—
—
LIFT DOWN - (CHECK WHEN DOWN AND ENABLE PADS ARE PUSHED ON THE PLATFORM CONTROL)
5.
Lift Down Valve Coil:Yel/Red, 2-6 wire - 24 volts
Tan, 4-1 wire - Ground
—
—
—
LIFT DOWN - (CHECK WHEN NO FUNCTION ARE ENABLED ON THE PLATFORM CONTROL)
6.
Lift Down Valve Coil:Yel/Red, 2-6 wire - 24 volts
Tan, 4-1 wire - 24 volts
—
—
—
Table 3-21. Pump Circuit