Perkins 1104D Operation And Maintenance Manual page 35

SEBU8172-04
• Fuel Pressure Sensor
• Engine Oil Pressure Sensor
• Primary Speed/Timing Sensor
• Secondary Speed/Timing Sensor
Coolant Temperature Sensor 1
The coolant temperature sensor monitors engine
coolant temperature. The output of the ECM (5) can
indicate a high coolant temperature through a relay
or a lamp. The coolant temperature sensor is used by
the ECM to determine initiation of the Cold Start
Condition.
Failure of the Coolant Temperature
Sensor
The ECM (5) will detect a failure of the coolant
temperature sensor. The diagnostic lamp will warn
the operator about the status of the coolant
temperature sensor. A failure of the coolant
temperature sensor will not cause a shutdown of the
engine or any horsepower change. In order to check
the correct operation of the sensor, refer to
Troubleshooting, "Engine Temperature Sensor Circuit
- Test".
Intake Manifold Air Temperature
Sensor 2
Note: This sensor can have two different locations.
The location will depend on the type of engine.
The intake manifold air temperature sensor
measures the intake air temperature. A signal is sent
to the ECM (5). The intake manifold air temperature
sensor is also used by the ECM to determine
initiation of the Cold Start Strategy.
Sensors and Electrical Components
In order to check the correct operation of the sensor,
refer to Troubleshooting, "EngineTemperature
Sensor Circuit - Test".
Intake Manifold Pressure Sensor 3
The intake manifold pressure sensor measures
pressure in the manifold. A signal is sent to the ECM
(5).
Fuel Pressure Sensor 4
The fuel pressure sensor measures the fuel pressure
in the fuel manifold. A signal is sent to the ECM (5).
Electronic Control Module 5
The ECM is the control computer of the engine. The
ECM provides power to the electronics. The ECM
monitors data that is input from the sensors of the
engine. The ECM acts as a governor in order to
control the speed and the power of the engine.
The ECM adjusts injection timing and fuel pressure
for the best engine performance, the best fuel
economy and the best control of exhaust emissions.
Primary Speed/Timing Sensor 6
If the ECM (5) does not receive a signal from the
primary speed/timing sensor , the "DIAGNOSTIC"
lamp will indicate a diagnostic fault code which will be
logged in the ECM memory.
If the ECM does not receive a signal from the primary
speed/timing sensor (7), the ECM will read the signal
from the secondary speed/timing sensor (8). The
ECM continually checks in order to determine if there
is a signal from both sensors.
Intermittent failure of the sensors will cause erratic
engine control.
Failure of the Primary Speed/Timing
Sensor
Correct operation of the primary speed/timing sensor
is essential. Software in the ECM protects against
reverse running of the engine. If the primary speed/
timing sensor fails there is no automatic protection
against reverse running. In some applications, it is
possible for the transmission to run the engine in
reverse. In this event, Stop the engine immediately.
Turn the keyswitch to the "OFF" position.
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Operation Section