The following sensor locations show typical 3176C Engine features. Due to individual applications, your engine may appear different from the illustrations.
| |
| Illustration 1 | g00532751 |
|
(1) Engine oil pressure sensor
(2) Coolant level sensor (3) Sensor for inlet manifold air temperature (4) Sensor for inlet manifold air pressure (5) Atmospheric pressure sensor (6) Coolant temperature sensor (7) Primary speed/timing sensor (8) Backup speed/timing sensor (9) Fuel pressure sensor (10) Fuel temperature 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 ground or supply.
- Measured reading of the sensor is out of specification.
A failure of the engine speed/timing sensor or the throttle position sensor may also be caused by one of the following malfunctions:
- The sensor is missing pulses.
- The sensor has extra pulses.
Atmospheric pressure sensor (5) measures the atmospheric pressure in the crankcase. A signal is sent to the Electronic Control Module (ECM).
Coolant level sensor (2) monitors the engine coolant level in order to detect a condition of low coolant level. The coolant level sensor provides information to the Electronic Control Module (ECM). The output from the Electronic Control Module (ECM) can indicate a low coolant level through a relay or a lamp. Coolant must be added to the cooling system in order to correct the condition.
Failure of Coolant Level Sensor
The failure of the coolant level sensor will not cause a shutdown of the engine or any horsepower change.
Coolant temperature sensor (6) monitors engine coolant temperature. This feature is used for engine system diagnostics with an output from the Electronic Control Module (ECM). The output of the Electronic Control Module (ECM) can indicate a high coolant temperature through a relay or a lamp. In addition, the sensor activates the cold start strategy which improves the startability of the engine.
| Coolant Temperature Sensor | |
| Minimum activation temperature | |
The switch opens as the coolant cools. A resetting procedure is not required.
Failure of Coolant Temperature Sensor
The Electronic Control Module (ECM) will detect the failure of the coolant temperature sensor. The diagnostic lamp will warn the operator about the status of the coolant temperature sensor. The related strategies of the coolant temperature will be disabled. The failure of the coolant temperature sensor will not cause a shutdown of the engine or any horsepower change.
If primary speed/timing sensor (7) cannot sense the engine speed, the "DIAGNOSTIC" lamp will indicate a diagnostic fault code which will be logged in the memory of the Electronic Control Module (ECM).
If the primary speed/timing sensor cannot sense the engine speed, the automatic default will use backup speed/timing sensor (8). The backup speed/timing sensor will be used until the primary speed/timing sensor is replaced.
Failure of Speed/Timing Sensor
Intermittent failure causes erratic engine control. The Electronic Control Module (ECM) will detect a failure of the primary speed/timing sensor. The operator will be warned through the diagnostic lamp.
Fuel pressure sensor (9) 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 temperature sensor (10) monitors the fuel temperature. A high fuel temperature can adversely affect the engine performance.
Inlet Manifold Air Pressure Sensor
The sensor for the inlet manifold air pressure (4) is located on the top right side of the engine. The sensor for the inlet manifold air pressure is located in front of the sensor for the inlet manifold air temperature.
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.
The boost pressure is determined from the difference in pressure between the sensor for the inlet manifold air pressure and the sensor for the atmospheric pressure (crankcase pressure).
Failure of the Sensor for the Inlet Manifold Air Pressure
The Electronic Control Module (ECM) will detect the failure of the sensor for the inlet manifold air pressure. The operator will be warned of the problem through the diagnostic lamp. The strategies that are related to the boost will be disabled. The failure of the sensor for the inlet manifold air pressure will not cause a shutdown of the engine or any horsepower change.
Inlet Manifold Air Temperature Sensor
The sensor for inlet manifold air temperature (3) measures the temperature of the air in the inlet manifold. The Electronic Control Module (ECM) monitors the signal of the sensor for the inlet manifold air temperature. The output of the Electronic Control Module (ECM) can indicate high inlet manifold air temperature through a relay or a lamp. The sensor for the inlet manifold air temperature will not cause a shutdown of the engine or any horsepower change.
Note: The sensor for the inlet manifold air temperature will be affected by the heat from the air in the inlet manifold 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 sensor for the inlet manifold air temperature may be significantly higher than the actual temperature of the air inside the inlet manifold until the inlet manifold cools.
Engine oil pressure sensor (1) can detect engine oil pressure for diagnostic purposes. The engine oil pressure sensor sends a signal to the Electronic Control Module (ECM).
The setpoint is dependent upon the engine rpm. 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 rpm. If the DERATE mode of the engine monitoring system is selected, the Electronic Control Module (ECM) will derate the engine power. The engine horsepower will be limited.
Failure of Engine Oil Pressure Sensor
The Electronic Control Module (ECM) will detect the failure of the engine oil pressure sensor. The diagnostic lamp warns the user about the status of the engine oil pressure sensor. The related strategies for the oil pressure will be disabled. The failure of the engine oil pressure sensor will not cause a shutdown of the engine or any horsepower change.
Note: The throttle position sensor is not shown in illustration 1.
The Throttle Position Sensor (TPS) sends a signal to the Electronic Control Module (ECM). The signal is required by the engine speed governor. The signal is used by the ECM in order to calculate the engine rpm that is desired. The TPS is calibrated during the initial installation of the engine.
Note: Some installations of the TPS do not need calibration. A TPS is not required for all applications.
Failure of the Throttle Position Sensor
An intermittent failure causes the engine rpm to drop. 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 engine rpm to low idle.