825843 Mercury DRIVE SHAFT

Illustration 1 g01425443
(1) Coolant temperature sensor
(2) Intake manifold pressure sensor
(3) Inlet air temperature sensor
(4) Fuel pressure sensor
(5) Electronic control module
(6) Primary position sensor
(7) Secondary position sensor
(8) Engine oil pressure sensor Illustration 2 shows the sensors and the ECM in position on the engine.
Illustration 2 g01425468Failure of Sensors
All Sensors
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 the specification.Programmable Monitoring System (PMS)
The Programmable Monitoring System determines the level of action that is taken by the Electronic Control Module (ECM) in response to a condition that can damage the engine. These conditions are identified by the ECM from the signals that are produced from the following sensors.
Coolant Temperature Sensor
Intake manifold Air Temperature Sensor
Intake manifold Pressure Sensor
Fuel Pressure Sensor
Engine Oil Pressure Sensor
Primary Speed/Timing Sensor
Secondary Speed/Timing SensorCoolant 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.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. In order to check the correct operation of the sensor, refer to Troubleshooting, "Engine speed/Timing sensor - Test".Secondary Speed/Timing Sensor 7
The signal from the secondary speed/timing sensor is used by the ECM (5) on engine start-up in order to check the stroke of the pistons. The secondary speed/timing sensor may be used by the ECM in order to operate the engine if the primary speed/timing sensor is faulty.In order to check the correct operation of the sensor, refer to Troubleshooting, "Engine speed/Timing sensor-Test".Engine Oil Pressure Sensor 8
Note: This sensor can have two different locations. The location will depend on the type of engine.The engine oil pressure sensor is an absolute pressure sensor that measures the engine oil pressure in the main oil gallery. The engine oil pressure sensor detects engine oil pressure for diagnostic purposes. The engine oil pressure sensor sends a signal to the ECM (5).Low Oil Pressure Warning
The setpoint for the low pressure warning is dependent upon the engine speed. The fault will be active and logged only if the engine has been running for more than 8 seconds. Very Low Oil Pressure Warning
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 (5) will derate the engine power. The engine horsepower will be limited.Failure of the Engine Oil Pressure Sensor
The ECM (5) 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. In order to check the correct operation of the sensor, refer to Troubleshooting, "5 Volt Sensor Supply Circuit - Test".