ELECTRICAL WIRING, SWITCHES, AND FUSES.

Figure 4-73. Hydraulic System Pressure Check

0-4000 psi scale at the discharge (pressure) line of

Figure 4-72. Fuses and Underdash Wiring

the hydraulic pump or at the hydraulic valve. See

figure 4-73.

4-63. ELECTRICAL WIRING, SWITCHES,

AND FUSES.

a. Connect the pressure line from the gauge to

t h e test port of the pump or valve by removing

plug from test port.

a. The wiring system on

the vehicle is a 12-volt

n e g a t i v e ground system.

Extreme care must be

b. Apply parking brake. Start engine and operate

taken when connecting an

outside source of power

at governed RPM. Hold tilt lever back until the

to any component for test

purposes, to observe the

pressure builds up and moves the pressure relief

proper ground polarity.

valve off its seat; avoid holding the tilt lever longer

t h a n is necessary to check pressure reading of

gauge. Take reading then release accelerator and

tilt lever.

Disconnect battery ground strap before

c. The pressure reading will indicate the setting

performing any service on electrical system.

of the relief valve. If reading taken is not

reasonably close to those listed in specifications,

b. Wiring circuitry and color codes are indicated

a p p r o p r i a t e repairs should be made. Report to

on the electrical schematic, figure 1-3.

designated authority.

c. Be sure to replace all light bulbs and

4-66. HYDRAULIC CIRCUIT FLOW TEST. If a

instruments with parts rated for 12-volt operation.

Schroeder Hydraulic Circuit Tester (Clark Part No.

d . Access to the fuses may be gained through

1800060) is available, the hydraulic relief valve

removal of the underdash cowling. Fuses are

setting and the rate of flow being delivered by the

identified in figure 4-72.

hydraulic pump may be checked as follows:

4-64. HYDRAULIC SYSTEM CHECKS.

a. Connect the pressure line from the tester to the

test port at the hydraulic pump, or at the test port

4-65. PRESSURE CHECK. The hydraulic relief

of the hydraulic valve. Remove sump tank breather

valve setting may be checked with a Mico

and insert the return line from the tester into the

Quadrigage (Clark Part No. 1800106) or, by

i n s t a l l i n g a conventional pressure gauge with a

sump tank.

4-50