PIPE 0878507 - Caterpillar

Illustration 1 g02035557
Schematic of the "Squeeze Pressure" SensorThis diagnostic code is recorded when the Machine ECM reads the signal voltage of the pressure sensor as being too low. The possible causes of this diagnostic code are listed below:
Wire M906-BU is shorted to ground.
The sensor has failed.
The ECM has failed. This situation is unlikely.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 active.
Observe the status of the diagnostic code. Disconnect the machine harness from the sensor.Expected Result:The diagnostic code will remain active if the sensor is not the cause of the problem. The sensor is the cause of the problem if the diagnostic code is NO longer active.Results:
OK - The diagnostic code remains active. The sensor has not failed. The machine harness may have failed or the Machine ECM may have failed. Proceed to Test Step 2.
NOT OK - The diagnostic code is NO longer active.Repair: The machine harness and the Machine ECM are operating properly. The sensor has failed. Replace the sensor.STOPTest Step 2. CHECK THE SIGNAL CIRCUIT FOR A SHORT TO GROUND.
The sensor remains disconnected from the machine harness.
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness connector J1 and J2 from the Machine ECM.
At the J1 machine harness connector, measure the resistance from contact J1-28 (M906-BU) to all source of ground.Expected Result: The resistance should be greater than 5 ohms. Results:
OK - The resistance is greater than 5 ohms. The machine harness is correct. Proceed to Test Step 3.
NOT OK - The resistance is less than 5 ohms.Repair: There is a short in the machine harness. The short is between the signal circuit (wire M906-BU) and the circuit with the low resistance measurement. Repair the machine harness or replace the machine harness. STOPTest Step 3. CHECK IF THE DIAGNOSTIC CODE REMAINS.
Clean the contacts of the harness connectors.
Reconnect all harness connectors.
Observe the status of the diagnostic code.
Operate the machine.
Observe the status of the diagnostic code.Expected Result:The diagnostic code is NO longer active.Results:
YES - The diagnostic code is NO longer active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor electrical connection and/or a short at one of the harness connectors. Resume normal machine operation.STOP
NO - The diagnostic code has not been corrected. The ECM has failed. Repair: A failure of the Machine ECM is unlikely. Exit this procedure and perform this diagnostic code procedure again. Replace the Machine ECM if the cause of the diagnostic code is not found. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".STOP