HUB 5F6537 - Caterpillar

Illustration 1 g01805693
Schematic of "Boom Cylinder Retract Pilot Pressure" sensorThis diagnostic code is associated with the "Boom Cylinder Retract Pilot Pressure" sensor. The FMI 08 means that the ECM has determined that the signal frequency or the signal pulse width is not within the expected range.The "Boom Cylinder Retract Pilot Pressure" sensor has an output frequency of approximately 500 Hz. The duty cycle of the signal changes as the position of the Rod End of the Boom Cylinder is changed. The duty cycle varies from approximately 19% at the minimum position to approximately 77% at the maximum position. The duty cycle is approximately 48% at the center position.The possible causes of this diagnostic code are listed below:
The pressure sensor has failed.
Intermittent connections or poor connections
Mechanical devices are loose.
The ECM has failed. This is unlikely.Note: The Machine ECM is equipped with LED indicators that serve as a self-diagnostic check. With the key start switch ON, the following can be determined by the ECM indicator lights:
If all of the LED lights are Off, voltage is not being supplied to the Machine ECM. Check for power to the ECM.
If the yellow LED is Flashing, a communication error exists on the "CAN" data-link circuit.
If the yellow LED is constantly On, the Machine ECM software may be missing / not loaded.
If the red LED is Flashing, the Machine ECM has failed and may need replacement. Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 3012 FMI 08 is active before performing this procedure.Note: Use