John Deere 318 - Manual (Page 312)

OIL PRESSURE LAMP CIRCUIT OPERATION
B1—Engine Oil Pressure M1—Starter Motor X2—Key Switch 1-Pin X16—Headlight Switch 2-Pin
Switch P5—Engine Oil Pressure Connector Connector
F1—20 Amp Fuse Lamp X3—Front PTO Switch 2-Pin X23—TDC Module 8-Pin
F3—25 Amp Circuit Breaker S1—Key Switch Connector Connector
G1—Battery X1—Key Switch 5-Pin
Connector
The purpose of the oil pressure lamp circuit is to
warn the operator when engine oil pressure is too low
for safe operation of the engine.
Oil pressure switch (B1) is a normally-closed switch.
When there is no oil pressure, such as when the
engine is not operating, the switch contacts are
closed. The closed contacts of the oil pressure switch
provide a path to ground for oil pressure lamp (P5).
When the key switch is turned to the RUN or START
position, current from the battery flows through circuit
breaker (F3), key switch (S1), and 20 amp fuse (F1).
From the fuse, current flows through oil pressure
lamp (P5), oil pressure switch (B1), then to ground,
lighting the oil pressure lamp. The lamp will stay lit
until either the key switch is turned to the OFF
position or engine oil pressure increases to the point
where the pressure switch contacts open, such as
during normal engine operation.
Fuse (F1) protects the oil pressure lamp circuit from
excessive current.
M77925
-19
-04MAR95
MX,159024020,9 -19-16MAY95
Component Location and Operation/Theory of Operation
TM1590 (17MAY95)
240-15-10
316, 318 & 420 Lawn and Garden Tractors
020895
240
15
10