ACTIVATING THE HYDRAULIC FAN WITH THE
DRBIIIT
Under the Engine Systems test heading, there is a
subheading. “Hydraulic fan solenoid test”, that has
the selections, on /off. Activating the fan with the
DRBIIIt will run the fan at 100% duty cycle, which
will help troubleshoot any system problems, and also
help with the deaeration procedure.
NOTE: Engine must be running to activate the fan
with the DRBIIIT.
RADIATOR COOLING FAN HYDRAULIC FLUID PATH
Hydraulic fluid is pumped through the power
steering pump, from the pump the fluid travels
though a high pressure delivery line to the fan drive
motor. As fluid is diverted through the G-rotors, rota-
tional motion is created as fluid moves from the high-
pressure (inlet) side of the motor to the low-pressure
(outlet) side. Fluid exiting the drive motor is divided
into two paths. Path one continues through a high
pressure delivery line to the vehicles steering gear to
provide steering assist. Path two sends fluid back to
the power steering pump through a low pressure
line. Fluid exits the steering gear under low pressure
and travels through a low pressure line to the power
steering fluid cooler to be cooled before being
returned back the the power steering fluid reservoir
(Fig. 20).
NOTE: There is a steering flow control valve located
in the fan drive motor. This valve operates like the
flow control valve found in the typical power steer-
ing pump. Because of the design of the valve steer-
ing assist can not be affected by the radiator
cooling fan even during fan drive failure.
REMOVAL
(1) Disconnect throttle body air inlet hose, remove
air cleaner housing assembly (Refer to 9 - ENGINE/
AIR INTAKE SYSTEM - REMOVAL).
(2) Raise vehicle on hoist.
Fig. 20 Hydraulic Fan Fluid Flow Circuit
1 - POWER STEERING RESERVOIR
2 - POWER STEERING PUMP
3 - HYDRAULIC FAN DRIVE ASSEMBLY
4 - FAN BLADE
5 - HYDRAULIC FAN CONTROL SOLENOID
6 - POWER STEERING OIL COOLER
7 - STEERING GEAR
7 - 22 ENGINE ZB
RADIATOR FAN (Continued)
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