Lull 944E-42 Service Manual - Manual (Page 724)

Electrical System
9.214 Model 644E-42/944E-42 Rev. 6/04
9.14.3 Hydraulic Oil Filter Pressure Switch
The hydraulic oil filter pressure switch (1) is threaded into
the top of the hydraulic oil filter, at the top rear of the
hydraulic oil reservoir.
The switch is connected to the wiring harness. When the
hydraulic oil system filter is clogged or restricted and the
internal pressure of the filter rises to 20 psi (1,4 bar), the
switch closes and the hydraulic oil filter restriction
indicator illuminates on the front dash panel. The vehicle
should be stopped and the engine revved at high idle for
five minutes. If the light remains illuminated or begins to
flicker ON and OFF at high idle, shut down the engine and
inspect the hydraulic system. (Refer to Section 9.10.8,
“Hydraulic Oil Filter Restriction Warning Indicator
Troubleshooting.”)
IMPORTANT: If the return filter is not serviced when the
indicator light comes ON, the return hydraulic oil will
bypass the filter when pressure reaches 25 psi (1,7 bar)
and return to the reservoir unfiltered.
Examine the fluid in the hydraulic oil sight glass (2) to
check whether there is a sufficient amount of fluid in the
system (the oil level should be at the mid-point of the sight
glass with all hydraulic cylinders retracted) and whether
the fluid is contaminated. Replace the hydraulic oil filter
as required.
a. Hydraulic Oil Filter Pressure Switch Removal
1. Unlock and open the engine cover (5).
2. If the vehicle has dual batteries, disconnect both
negative battery cables (7 and 8) from both
batteries.
To access the lower battery (9), loosen the knob (10)
far enough so that the lip (11) on the upper battery
box clears the knob. Lift up the upper battery box (12)
and swing it out, so that the box clears the hydraulic
tank support bracket, to gain access to the lower
negative battery cable (7). Disconnect the lower
negative battery cable.
MU3610
1
2
3
4
Front
4110390
1.
2.
OU0780
6
6
5
MU0650
7
8
9
10
11
12