Illustration 1, Illustration 2, Illustration 3, and Illustration 4 show the typical locations of the sensors for a 3176B Industrial Engine. Specific engines may appear different from the illustrations due to differences in applications.
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| Illustration 1 | g00578923 |
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Right side view of engine (1) Oil pressure sensor | |
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| Illustration 2 | g00578926 |
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Left side view of engine (2) Fuel temperature sensor (3) Fuel pressure sensor | |
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| Illustration 3 | g00578927 |
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Front view of engine (4) Coolant temperature sensor (5) Speed/timing sensor | |
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| Illustration 4 | g00578924 |
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Top view of engine (6) Atmospheric pressure sensor (7) Inlet manifold air temperature sensor (8) Inlet manifold air pressure sensor | |
A failure of any of the sensors may be caused by one of the following malfunctions:
- Sensor output is open.
- Sensor output is shorted to "- battery" or "+ battery".
- Measured reading of the sensor is out of specification.
Atmospheric pressure sensor (6) measures the atmospheric pressure in the crankcase. A signal is sent to the Electronic Control Module (ECM).
| Atmospheric Pressure Sensor | |
| Operating pressure range for the atmospheric pressure sensor | |
Coolant temperature sensor (4) monitors engine coolant temperature. This feature is used for engine system diagnostics with an output from the ECM. The output of the ECM can indicate a high coolant temperature through a relay or a lamp.
Failure of the Coolant Temperature Sensor
The ECM will detect a failure of the coolant temperature sensor. The diagnostic lamp will warn the operator about the status of the coolant temperature sensor. Coolant temperature related strategies will be disabled if a failure occurs. A failure of the coolant temperature sensor will not cause a shutdown of the engine or any horsepower change.
The engine oil pressure sensor (1) is mounted in the front of the cylinder block. There is no oil line that is connected to the sensor. Low oil pressure closes the switch. The oil pressure sensor senses oil pressure at the bearing oil gallery. There is no resetting procedure.
Note: The oil pressure switch may close at
The setpoint is dependent upon the engine speed. The fault will be active and logged only if the engine has been running for more than 15 seconds.
The very low oil pressure setpoint is dependent upon the engine speed. If the DERATE mode of the engine monitoring system is selected, the ECM will derate the engine power. The engine horsepower will be limited.
Failure of the Engine Oil Pressure Sensor
The ECM will detect failure of the engine oil pressure sensor. The diagnostic lamp warns the user about the status of the engine oil pressure sensor. The engine oil pressure related strategies will be disabled in the event of a failure of the engine oil pressure sensor. A failure of the engine oil pressure sensor will not cause a shutdown of the engine or any horsepower change.
If the ECM does not receive a signal from engine speed/timing sensor (5), the "DIAGNOSTIC" lamp will indicate a diagnostic fault code which will be logged in the ECM memory.
Intermittent failure of the sensor will cause erratic engine control.
Fuel pressure sensor (3) monitors the fuel filter outlet pressure. Low fuel pressure or high fuel pressure will not cause a shutdown of the engine or any horsepower change. Fuel pressure that is outside of the normal range will affect the engine performance. If the fuel filter outlet pressure is low, the fuel filter may need to be replaced.
| Fuel Pressure Sensor | |
| Minimum allowable pressure of the fuel transfer pump at full load speed | |
| Minimum allowable pressure in the fuel manifold at full load speed | |
Fuel temperature sensor (2) monitors the fuel temperature. Fuel temperature is monitored in order to adjust the fuel rate so that the engine will deliver consistent power. The fuel temperature sensor can also be used to warn the operator of excessive fuel temperature. A high fuel temperature can adversely affect the engine performance.
| Fuel Temperature Sensor | |
| Operating range of the fuel temperature sensor for activation of the power correction by the ECM | |
Inlet Manifold Air Temperature Sensor
The inlet manifold air temperature sensor (7) measures the inlet manifold air temperature. The Electronic Control Module (ECM) monitors the signal from the inlet manifold air temperature sensor. The output of the ECM can indicate high inlet manifold air temperature through a relay or a lamp. The inlet manifold air temperature sensor will not cause a shutdown of the engine or any horsepower change.
Note: The inlet manifold air temperature sensor will be affected by the heat that is conducted from the inlet manifold. This is true when the engine is idling and after the engine is shut off. This warm-up is due to the lack of coolant circulation through the engine. The reading from the inlet manifold air temperature sensor may be significantly higher than the actual temperature of the air inside the inlet manifold until the inlet manifold cools.
Inlet Manifold Air Pressure Sensor
The air/fuel ratio control utilizes actual engine speed and actual boost pressure (inlet manifold air pressure) in order to control the transient smoke level. When the throttle is increased and when the engine demands more fuel, the fuel limit is controlled in order to reduce overall smoke levels of the engine exhaust.
The Electronic Control Module (ECM) controls injection timing and the amount of fuel that is injected.
Note: The inlet manifold air pressure sensor (8) is located on the top right side of the engine. The sensor is located in front of the inlet manifold air temperature sensor.
The boost pressure is determined from the difference in pressure between the inlet manifold air pressure sensor and the atmospheric pressure sensor (crankcase pressure).
Failure of the Inlet Manifold Air Pressure Sensor
A failure of the inlet manifold air pressure sensor may have occurred if any of the following conditions are present:
- The output of the inlet manifold air pressure sensor is open.
- The output of the inlet manifold air pressure sensor is shorted to ground or to supply.
- The reading of the inlet manifold air pressure sensor is out of specification.
The ECM will detect the failure of the inlet manifold air pressure sensor. The operator will be warned of the problem through the diagnostic lamp. The strategies that are related to the boost will be disabled. The inlet manifold air pressure sensor failure will not cause a shutdown of the engine or any horsepower change.
The Throttle Position Sensor (TPS) sends a signal to the ECM. The signal from the TPS is required in order to govern engine speed. The signal from the TPS is used by the ECM in order to calculate the desired engine speed. The TPS is calibrated during the initial installation of the engine.
Note: The throttle position sensor is not shown in the illustration.
Failure of the Throttle Position Sensor
An intermittent failure in the TPS causes the engine speed to vary erratically. The ECM will perform the following process:
- The ECM will detect the failure of the TPS.
- The ECM will warn the operator of the failure through the diagnostic lamp.
- The ECM will set the desired engine speed to low idle.