821300 25 Mercruiser SCREW, (M6 x 25)

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Schematic for the engine speed/timing sensorsTest Step 1. Check for Diagnostic Codes
Connect Cat ET to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".
Turn the keyswitch to the ON position.
Start the engine and run the engine until the engine is at the normal operating temperature.Note: If the engine will not start, monitor the engine rpm on Cat ET while the engine is being cranked. Cat ET may need to be powered from another battery while the engine is being cranked.
Look for these codes on Cat ET:
190-08
342-08Expected Result:One or both of the diagnostic codes that are listed above are logged or active.Note: If the engine will not start and Cat ET displayed 0 rpm during cranking, select "No Engine rpm".Results:
No Engine rpm - Engine rpm is not indicated on Cat ET. Proceed to Test Step 2.
190-08 or 342-08 code - There is an active diagnostic code or a logged diagnostic code for an engine speed/timing sensor. Proceed to Test Step 4.
No codes - Neither code is active or logged.Repair: Refer to the appropriate symptoms in Troubleshooting, "Troubleshooting Without a Diagnostic Code".STOPTest Step 2. Check the Installation of the Sensor Assembly
Turn the keyswitch to the OFF position.
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Typical engine speed/timing sensor (1) Engine (2) Flange
Visually inspect each sensor assembly without removing the sensor assembly from the engine. Flange (2) must be flush against engine (1) in order to ensure proper operation.Note: The flange cannot be replaced separately.
Remove the suspect sensor assembly from the engine.
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Typical engine speed/timing sensor (3) O-ring
Ensure that one O-ring (3) is installed on the sensor. Check the O-ring for damage. Replace the O-ring, if necessary.Results:
OK - The sensor's components are OK.Repair: Perform the following procedure in order to properly install the sensor assembly:
Lubricate the O-ring with engine oil.
Fully seat the sensor assembly in the engine.Note: If the sensor assembly will not fully seat into the engine, replace the sensor assembly.
Tighten the bracket bolt.
Connect the sensor's electrical connectors. Verify that the connectors are latched on both sides.
Ensure that the harness is properly secured, and that the tie-wraps are placed in the correct location. Proceed to Test Step 3.
Not OK - At least one of the sensor assembly's components is not OK.Repair: Obtain a new sensor assembly. Perform the following procedure in order to properly install the sensor assembly:
Lubricate each O-ring with engine oil.
Fully seat the sensor assembly in the engine.Note: If the sensor assembly will not fully seat into the engine, replace the sensor assembly.
Tighten the bracket bolt.
Connect the sensor's electrical connectors. Verify that the connector is latched.
Ensure that the harness is properly secured, and that the tie-wraps are placed in the correct location.Verify that the problem is resolved.STOPTest Step 3. Inspect the Electrical Connectors and the Wiring
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Engine components for the engine speed/timing sensors (1) J2/P2 ECM connector (2) J402/P402 connectors for the secondary engine speed/timing sensor (3) J401/P401 connectors for the primary engine speed/timing sensor
Thoroughly inspect connectors (1), (2), and (3). Refer to Troubleshooting, "Electrical Connectors - Inspect".
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P2 terminals that are associated with the engine speed/timing sensors (P2-25) Primary engine speed/timing − (P2-35) Primary engine speed/timing + (P2-46) Secondary engine speed/timing + (P2-47) Secondary engine speed/timing − (P2-92) Shield
Perform a 45 N (10 lb) pull test on each of the wires that are associated with the engine speed/timing sensors.
Check the allen head screw on each ECM connector for the proper torque. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the