Komatsu 830E-AC Shop Manual page 198

Pressure Switch
The pressure switch (2, Figure 2-3) is a 17.2 kPa (2.5
psi), normally closed (N.C.) switch, located so that it
can sense oil pressure after the engine oil has
passed through the filters. (Normally, this location is
the cam cover at the rear of the engine block.)
Check Valve
The oil pressure supply hose will have a check valve
installed between the prelube pump and the engine.
The check valve prevents the passage of oil from the
engine back through the prelube pump to the pan
after the engine is started. Check valve leakage back
to the prelube pump will cause extensive damage to
the pump.
Timer Solenoid
The timer solenoid (3, Figure 2-3) controls the prelu-
brication cycle. Current is supplied to the timer
through the key switch. The ground path is com-
pleted by the normally closed pressure switch (2).
When the switch opens, current is redirected to the
engine cranking motor solenoids (8) for engine
cranking.
DO NOT Attempt to jump start the truck using the
terminals on the timer solenoid. INTERNAL DAM-
AGE TO TIMER WILL RESULT.
D2-8
MAINTENANCE
Prelube system maintenance should be performed
annually or at 5000 hour intervals as described
below.
Prelube System Operation Checks
Verify system operates according to the two phases
of operation as listed in "Troubleshooting Prelube
Cranking Motor Circuit" on the following page. If a
problem exists, refer to the list of problems and pos-
sible causes for troubleshooting system components.
If system is operating properly, continue with the
inspection of component parts below:
Check Valve
Verify no internal leakage exists in the check valve
when the engine is running. Check valve leakage
back to the prelube pump will cause extensive dam-
age to the pump.
If check valve replacement is required, ensure the
valve is installed with the arrow pointed toward the
engine, and NOT toward the pump.
Timer Solenoid
Inspect timer solenoid for physical damage and to
verify wiring is in good condition.
24 VDC Electric Supply System D02034