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| Illustration 1 | g02618243 |
(1) Coolant Temperature Sensor
(2) Primary Speed/Timing Sensor
(3) Air Inlet Manifold Pressure Sensor
(4) Temperature Sensor for the Air Intake Manifold
(5) Magnetic Pickup (RH Side of Flywheel Housing)
(6) Oil Pressure Sensor
(7) Crankcase Pressure Sensor
(8) Atmospheric Pressure Sensor
(9) Secondary Speed/Timing 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.
Inlet air temperature sensor (2) measures the temperature of the inlet air. The Electronic Control Module (ECM) monitors the signal of the inlet air temperature sensor. The output of the ECM can indicate high inlet air temperature through a relay or a lamp. The inlet air temperature sensor will not cause a shutdown of the engine or any horsepower change.
If the ECM 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, the ECM will read the signal from the secondary speed/timing sensor. The ECM continually checks in order to determine if there is a signal from both sensors (6 and 7). If either sensor fails, the faulty sensor should be replaced.
Intermittent failure of the sensors will cause erratic engine control.
Coolant temperature sensor (1) monitors engine coolant temperature. This feature is used for the 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. Strategies that are related to the coolant temperature sensor 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.