18856M Mercury KEY

Illustration 1 g01265105
Schematic for speed/timing sensors
Test Step 1. Check for Active Diagnostic Codes
Remove the electrical power from the ECM.
Connect Caterpillar Electronic Technician (ET) to the service tool connector.
Restore the electrical power to the ECM.
Start the engine and run the engine. The problem may occur when the engine is at any operating temperature. However, the problem is more likely to occur when the engine is at the normal operating temperature.
If the engine will not start, monitor the engine speed 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. This is done so that Cat ET will not reset. Note: Upon initial cranking, the status for engine speed may indicate that the engine speed signal is abnormal. This message should be replaced with an engine speed once the ECM is able to calculate a speed from the signal.
Check for one of the following logged diagnostic codes or active diagnostic codes: Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
190-08 Engine Speed is abnormal
342-08 Secondary Engine Speed signal is abnormalExpected Result:One of the above codes are active or logged.Results:
No engine rpm - Engine rpm is not indicated on Cat ET. Proceed to Test Step 2.
Active or logged 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
Remove the electrical power from the ECM.
Illustration 2 g01194044
Sensor installation
(1) Mounting surface
(2) Flange
(3) Bracket
Visually inspect the sensors without removing the sensor assembly from the engine. Flange (2) must be flush against mounting surface (1) in order to ensure proper operation. Inspect bracket (3). Verify that the bracket securely holds the flange of the sensor flush against the mounting surface.Verify that the bracket is not bent. If the bracket is bent or if an obstruction is preventing the sensor assembly from being installed correctly, the engine will not start.Note: The bracket cannot be replaced separately.
Illustration 3 g01142103
Engine speed/timing sensors
(4) Bracket
(5) Secondary speed/timing sensor
(6) Mounting plate
(7) O-ring seals
(8) Bracket
(9) Primary speed/timing sensor
Remove the suspect engine speed/timing sensor from the engine.
Ensure that O-ring seals (7) are installed on sensors (5) and (9), and on mounting plate (6). Ensure that the O-ring seals are free of damage. Expected Result:All of the O-ring seals are properly installed and free of damage. The bracket is free of damage.Results:
OK - The O-ring seals are properly installed. The bracket and the seals are free of damage.Repair: Perform the following procedure in order to properly install a sensor assembly:
Lubricate the O-ring seals with oil.
Fully seat each sensor into the housing. Note: If the sensor assembly will not fully seat into the engine, replace the sensor assembly.
Tighten the bolt for brackets (4) and (8).
Connect the connector and verify that the latch tab of the connector is securely latched.
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:Note: Do not switch the positions of the sensors. The sensors are not interchangeable. A timing calibration is not required when the sensors are replaced.
Lubricate each O-ring with oil.
Fully seat the sensor into the housing.
Tighten the bracket bolt.
Connect the connector and verify that the latch tab of the connector is securely 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
Remove the electrical power from the ECM.
Illustration 4 g01194100
Left side engine view (typical example)
(10) Primary speed/timing sensor connector
(11) Secondary speed/timing sensor connector
(12) P2 ECM connector