Lift Down Function Inoperative; Lift Up Function Inoperative - JLG T350 Troubleshooting Manual

1.13 LIFT DOWN FUNCTION INOPERATIVE

Step Pretest Instructions
1.13.1
1.13.2

1.14 LIFT UP FUNCTION INOPERATIVE

Step Pretest Instructions
1.14.1
1.14.2 Engage enable and lift up
switch
1.14.3 Install a 0 to 5000 PSI (345
bar) pressure gauge at the
manifold G port
1.14.4 Plumb a 0 to 5000 PSI (345
bar) pressure gauge into the
manifold P port
1.14.5 Plumb a 0 to 5000 PSI (345
bar) pressure gauge into the
hose from the lift up cylinder
cap end.
3121203
Test
Basic check of likely causes
Does Manual Descent lower
the boom?
Test
Basic check of likely causes
DC - Is pump motor running?
Gas - Is engine running at high
idle
Engage the enable and Lift up
switch. Check the pressure.
Engage the enable and Lift up
switch. Check pressure at
manifold P port
Check pressure at lift cylinder
while activating lift up at
ground controls
T350 T500J
SECTION 1 - TROUBLESHOOTING BY FUNCTION
Result
Yes
No
Result
Yes
No
Yes
No
Above Min. Lift Up Pressure psi
(bar)
Below Min. Lift Up Pressure psi
(bar)
Above Min. Lift Up Pressure psi
(bar)
Below Min. Lift Up Pressure psi
(bar)
Above Min. Lift Up Pressure psi
(bar)
Below Min. Lift Up Pressure psi
(bar)
Corrective Action
Possible Causes: 4.1.33, 4.1.37, 4.1.49
Possible Causes: 4.1.38, 4.1.59, 4.1.48,
4.1.10
Possible Causes: 4.1.41, 4.1.47, 4.1.10
Corrective Action
Possible Causes: 4.1.32, 4.1.33, 4.1.37
Go to step 1.14.3
See 1.2 Pump Motor Will Not Operate -
DC Powered Models
Go to step 1.14.3
See 1.8 Engine High Idle Inoperative -
Engine Models
Go to step 1.14.5
Go to step 1.14.4
Possible Causes: 4.1.38, 4.1.45,
4.1.74, 4.1.40, 4.1.10, 4.1.43
Possible Causes: 4.1.10, 4.1.46,
4.1.47, 4.1.74, 4.1.45, 4.1.39
Possible Causes: 4.1.49, 4.1.48, 4.1.41
Possible Causes: 4.1.42, 4.1.58
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