TOHATSU BFT75A Service Manual page 589

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TECHNICAL FEATURES
ABNORMAL OIL PRESSURE DETECTION
In a conventional system, the ECM uses two EOP switches (low/high pressure) in order to detect an abnormal oil pressure
according to the operating condition that varies with the engine speed and engine temperature.
On this newly introduced oil pressure alert system, the ECM detects linear change of oil pressure by the EOP sensor, constantly
compares the constantly changing detected value with the normal value depending on engine speed and temperature, in order to
find an abnormal oil pressure.
EOP SWITCH
OIL PRESSURE
(1)
NE1
(1): Controlled by the EOP switch (low pressure side)
(2): Intermediate area (low/high switches depending
on operating condition)
(3): Controlled by the EOP switch (high pressure side)
FAIL-SAFE OPERATION WHEN ABNORMAL OIL PRESSURE IS DETECTED
When the ECM detects an abnormal oil pressure, it conducts the following fail-safe operations.
1. Turns OFF the oil indicator light (Green)
2. Sounds the warning buzzer continuously
3. Limits the engine speed below 1,800 min
When the abnormal oil pressure is cleared, the ECM will turn ON the oil indicator light (Green) and stops the warning buzzer, then
gradually increases the engine speed to normal operating speed.
Abnormal oil pressure detected:
CRUISING
SPEED
1,800 min-1
(rpm)
20-4
(3)
(2)
ENGINE SPEED
NE2
-1
(rpm)
ECM conducts the fail-safe operations.
1) Turns OFF the oil indicator light (Green):
2) Sounds the warning buzzer continuously:
3) Limits the engine speed below 1,800 min-1 (rpm)
EOP SENSOR
OIL PRESSURE
Oil pressure returns to normal
ECM conducts the normal operation.
1) Turns ON the oil indicator light (Green):
2) Stops the warning buzzer:
3) Increases the engine speed to normal speed
Time
SPECIFIED VALUE
DETECTED VALUE
Alert system
operates if the
detected value is
lower than specified.
ENGINE
SPEED
ENGINE
TEMPERATURE