GRAPPLE AR 1002757 - Caterpillar

Illustration 1 g02033089
Schematic of the "Boom Cylinder Head Pressure" SensorThis diagnostic code is recorded when the Machine ECM reads the signal of the pressure sensor (wire H446-PK) as being not valid.The possible causes of this diagnostic code are listed below:
Wire H446-PK is shorted.
The sensor is not installed correctly.
The sensor has failed.
The ECM has failed. This is unlikely.Note: Ensure that the diagnostic code for the sensor is active.Test Step 1. CHECK THE SENSOR.
Turn the disconnect switch and the key start switch to the ON position.
Ensure that the diagnostic code is present.
Observe the status of the diagnostic code. Disconnect the machine harness from the sensor.Expected Result:If the sensor is not the cause of the diagnostic code, the diagnostic code remains present. If the sensor has failed, the diagnostic code is NO longer present.Results:
OK - The diagnostic code remains present. The sensor has not failed. The machine harness or the Machine ECM may have failed. Proceed to Test Step 2.
NOT OK - The diagnostic code is NO longer present. The machine harness is correct and the Machine ECM is operating properly. The sensor has failed.Repair: Replace the sensor. Verify that the new sensor corrects the problem.STOPTest Step 2. CHECK FOR A SHORT IN THE HARNESS.
Turn the key start switch and the disconnect switch to the OFF position.
The machine harness remains disconnected from the sensor.
Disconnect the J1 and J2 connector from the Machine ECM.
At the J1 connector for the ECM, measure the resistance from contact J1-36 (wire H446-PK) to all other J1 and J2 contacts.Expected Result:The resistance should be greater than 5 ohms.Results:
YES - Each resistance measurement is greater than 5 ohms. The harness is correct. The Machine ECM has failed.Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this diagnostic code procedure again. If the cause of the diagnostic code is not found, replace the ECM. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".STOP
NO - The resistance is not greater than 5 ohms for each measurement. There is a short in the harness.Repair: The short is between the signal circuit (wire H446-PK) and the circuit with the low resistance measurement. Repair the harness or replace the harness.STOP