PUMP GP-PISTON 1991064 - Caterpillar

Illustration 1 g02683996
Schematic of the Implement Pump Discharge Pressure Sensor
This diagnostic code is associated with the Implement Pump Discharge Pressure Sensor. The sensor produces a PWM signal. 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 Implement Pump Discharge Pressure Sensor receives power from the 8V power supply of the Implement ECM. The sensor is connected to ground from the 8V sensor return of the Implement ECM. The illustration above indicates the power and ground connections for the position sensor.The Implement Pump Discharge Pressure Sensor provides a PWM output signal in the range of 5% to 95% to the Implement ECM. The duty cycle of the PWM signal corresponds to the monitored pump pressure.If the ECM detects the frequency is less than 400 Hz or greater than 600 Hz, an FMI 08 code will be activated.The approximate PWM duty cycles listed pump pressures are in the following table.
Table 1
Implement Pump Discharge Pressure Sensor
Pressures vs. Temperature
Pressure Temperature
1182 kPa (171.43 psi) −40° C (−40° F) to 0° C (32° F)
593 kPa (86 psi) 0° C (32° F) to 40° C (104° F)
490 kPa (71.06 psi) 40° C (104° F) to 100° C (212° F)
671 kPa (97.32 psi) 100° C (212° F) to 125° C (257° F) The possible causes of this diagnostic code are listed below:
The sensor has failed.
Intermittent connections or poor connections
The ECM has failed. This condition is unlikely.Note: If a CID 0041 diagnostic code for the 8V power supply has been activated, correct the problem before proceeding with this procedure.Note: Before performing this procedure, inspect the harness connectors that are involved in the circuit. Poor connections can often be the cause of a problem in an electrical circuit. Inspect the connections for the following:
Connections are clean.
Connections are secure.
Connections are in good condition.Note: If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure.Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the problem has been corrected.Test Step 1. CHECK THE DUTY CYCLE AND THE SIGNAL FREQUENCY AT THE SENSOR
Turn the key start switch and the disconnect switch to the OFF position.
At the machine harness connector for the pressure sensor, use a 151-6320 Removal Tool to remove the signal wire K904-GN(Green) and the socket at contact 3 from the harness connector. The connector for the machine harness J1 remains connected to the connector of the pressure sensor.
At the back of the pressure sensor connector, insert 7X-1710 Multimeter Probes along the ground contact 2 and the signal contact 3.
Turn the disconnect switch and the key start switch to the ON position.
Measure the frequency of the signal from the sensor.
Observe the measurement and wiggle the connector of the sensor. Gently pull on the wires and wiggle the wires.
Measure the duty cycle of the sensor at the connector