GLASS-REAR 5337758 - Caterpillar

Illustration 1 g02065975
Schematic of "Boom Down Control Pressure" SensorThis diagnostic code is associated with the "Boom Down Control Pressure" Sensor. The FMI 08 diagnostic code means that the Machine ECM has determined that the signal frequency or the signal pulse width is not within the expected range.The "Boom Down Control 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 Machine ECM has failed. This is unlikely.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 the 146-4080 Digital Multimeter for the measurements in this procedure. Test Step 1. CHECK FOR POWER AT THE "BOOM DOWN CONTROL PRESSURE" SENSOR
Do not disconnect the harness connector from the pressure sensor.
Turn the key start switch and the disconnect switch to the ON position.
At the back of the harness connector for the pressure sensor, insert a 7X-1710 Multimeter Probe along the wire that supplies the voltage J850-WH (contact 1).
Measure the voltage from contact 1 (wire J850-WH) to frame ground.Expected Result:The voltage is approximately 8 VDC.Results:
OK - The voltage is approximately 8 VDC. Proceed to Test Step 2.
NOT OK - The voltage is not approximately 8 VDC. The circuit is open. Repair: Repair the machine harness or replace the machine harness.STOPTest Step 2. CHECK THE SIGNAL CIRCUIT OF THE "BOOM DOWN CONTROL PRESSURE" SENSOR FOR THE CORRECT DUTY CYCLE
Turn the key start switch and the disconnect switch to the OFF position.
At the back of the harness connector for the sensor, remove the 7X-1710 Multimeter Probe from contact 1 (wire J850-WH) and insert the probe along the signal wire M844-OR (contact 3).
At the back of the harness connector for the sensor, insert a 7X-1710 Multimeter Probe along the ground wire 235-BK (contact 2).
Turn the disconnect switch and the key start switch to the ON position.
Monitor the duty cycle of the pressure sensor with the 146-4080 Digital Multimeter .
Without disconnecting the pressure sensor or the hardware that is associated with the pressure sensor from the machine, move the boom of the machine through the entire range of motion.Expected Result:The value of the duty cycle of the pressure sensor responds in the manner that is described at the begining of this procedure.Results:
OK - The value of the duty cycle of the pressure sensor responds correctly. The pressure sensor is operating correctly. Proceed to Test Step 3.
NOT OK - The value of the duty cycle of the pressure sensor does not respond correctly. The pressure