Boom Functions - Genie GTH-636 Service Manual

Section 5 • Troubleshooting
TROUBLESHOOTING
1-3

Boom Functions

Joystick (4-way) Circuit
Symptom:
Slow or no boom functions
Check the Pilot Pressure
1 GTH-636, GTH-644, GTH-842 and GTH-844:
Install a 0 to 3500 psi / 0 to 250 bar pressure
gauge into test port 3 at the side of the
hydraulic tank.
Note: There are four test ports at the hydraulic
tank. Test port 1 is closest to the tank; test port 4 is
farthest from the tank.
2 GTH-1048 and GTH-1056: Install a
0 to 3500 psi / 0 to 250 bar pressure gauge into
test port 5 at the side of the hydraulic tank.
Note: There are six test ports at the hydraulic tank.
Test port 1 is closest to the tank; test port 6 is
farthest from the tank.
GTH-1048
GTH-1056
a test port
b test port 4
c test port 3
d test port 1
a b c d
5 - 6 GTH-636 • GTH-644 • GTH-842 • GTH-844 • GTH-1048 • GTH-1056
GTH-636
GTH-644
GTH-842
GTH-844
6
b c d
3 Check the pilot pressure. Start the engine and
allow the engine to idle.
Result:
GTH-636, GTH-644, GTH-842 and GTH-844:
The pressure gauge reads 500 psi / 34.5 bar.
The pressure setting is correct. Proceed to step
4.
GTH-1048 and GTH-1056: The pressure
gauge reads 400 psi / 27.6 bar. The pressure
setting is correct. Proceed to step 4.
Result:
GTH-636, GTH-644, GTH-842 and GTH-844:
The pressure gauge fails to read
500 psi / 34.5 bar. Adjust or replace the
pressure reducing/relief valve (schematic item
FB). Refer to Repair Procedure 7-18, How to
Set the Boom System Pilot Pressure.
GTH-1048 and GTH-1056: The pressure
gauge fails to read 400 psi / 27.6 bar. Adjust or
replace the pressure reducing/relief valve
(schematic item FB). Refer to Repair Procedure
7-18, How to Set the Boom System Pilot
Pressure.
Result: The pressure reading is
200 psi / 13.8 bar or lower. The pressure
reducing/relief valve (schematic item FB) is
faulty. Replace the valve.
4 GTH-636, GTH-1048 and GTH-1056: Stop the
engine. Proceed to step 5.
GTH-644, GTH-842 and GTH-844: Stop the
engine. Proceed to step 13.
June 2007
REV B
Part No. 97487