Genie GTH-636 Service Manual page 153

June 2007
REV A
Check the Control Block
10 Install a 0 to 3500 psi / 0 to 250 bar pressure
gauge into test port 2 at the side of the
hydraulic tank.
Note: GTH-636, GTH-644, GTH-842 and
GTH-844: 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.
Note: GTH-1048 and GTH-1056: 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
11 Check the steer pressure. Start the engine and
allow the engine to idle.
12 Without operating any machine controls,
observe the reading on the pressure gauge.
Result: The pressure gauge reads
2250 psi / 155 bar. The pressure setting is
correct.
Result: The pressure gauge shows a fluctuating
pressure reading. The steer relief valve
(schematic item FC) is faulty. Replace the
valve.
Result: The pressure gauge reads less than
1000 psi / 69 bar. The steer relief valve
(schematic item FC) is faulty. Replace the
valve.
Part No. 97487 GTH-636 • GTH-644 • GTH-842 • GTH-844 • GTH-1048 • GTH-1056
GTH-636
GTH-644
GTH-842
GTH-844
6
b c d
Check the Pilot Pressure
13 Stop the engine.
14 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.
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.
15 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.
GTH-1048 and GTH-1056: The pressure
gauge reads 400 psi / 27.6 bar. The pressure
setting is correct.
Result: The pressure gauge shows a fluctuating
pressure reading. Proceed to the next step.
Result: The pressure reading is
200 psi / 13.8 bar or lower OR the pressure
reading is 1000 psi / 69 bar or higher. The
pressure reducing/relief valve (schematic item
FB) is faulty. Replace the valve.
16 Turn the engine off.
17 Tag, disconnect and plug the hydraulic hose
from port C of the control block. Cap the fitting.
18 Start the engine and allow the engine to idle.
Result: The pressure gauge shows a fluctuating
pressure reading. The pressure reducing/relief
valve (schematic item FB) is faulty. Replace the
valve.
Result: The pressure reading does not
fluctuate. Troubleshoot the parking brake or the
joystick circuits.
Section 5 • Troubleshooting
TROUBLESHOOTING
5 - 5