LINK AND SEAL GROUP 7K9927 - Caterpillar

Illustration 1 g02437037
Schematic of the Steering Pump Oil Pressure Sensor 1
This diagnostic code is associated with the Steering Pump Oil Pressure Sensor 1. The sensor produces an analog signal. The signal wire (N931-GY(Grey)) connects to contact J1-36 of the Implement ECM. The FMI 03 is recorded when the Implement ECM reads the signal from the pressure sensor (wire N931-GY(Grey)) and the voltage is below normal.The Steering Pump Oil Pressure Sensor 1 provides an analog voltage input signal to the Implement ECM. The Implement ECM 5 VDC power supply is used to power the sensor. This sensor provides a 0.5 VDC to 4.5 VDC voltage signal to the ECM that will correspond to the monitored pump pressure.The approximate signal voltages for the listed pump pressures are in the following table.
Table 1
Steering Pump Oil Pressure Sensor 1 Signal Voltage versus Pressure
Pressure Signal Voltage Pressure Signal Voltage
6895 kpa (1000 psi) 0.9 VDC 24.1 mpa (3500 psi) 2.9 VDC
13.8 mpa (2000 psi) 1.7 VDC 25.6 mpa (4000 psi) 3.3 VDC
17.2 mpa (2500 psi) 2.1 VDC 31.0 mpa (4500 psi) 3.7 VDC
20.7 mpa (3000 psi) 2.5 VDC 34.5 mpa (5000 psi) 4.0 VDC The possible causes of this diagnostic code are listed below:
The signal circuit is shorted to ground.
The supply circuit to the sensor is shorted high.
The pressure sensor has failed.
The ECM has failed. This condition is unlikely.Note: Ensure that the CID 0429 FMI 04 diagnostic code is active. This procedure can cause new diagnostic codes to be recorded. Ignore these created diagnostic codes. When the procedure is completed, clear the created diagnostic codes.Note: Ensure that all required calibrations are performed after the diagnostic code has been corrected.Test Step 1. CHECK THE SENSOR
Turn the disconnect switch and the key start switch to the ON position.
Ensure that the CID 0429 FMI 04 diagnostic code is active.
Observe the status of the diagnostic code.
Disconnect the sensor from the machine harness.The CID 0429 FMI 04 diagnostic code will remain active if the sensor is not the cause of the diagnostic code. The sensor is the cause of the diagnostic code if the diagnostic code is no longer active.Expected Result:The CID 0429 FMI 04 diagnostic code remains active.Results:
OK - The CID 0429 FMI 04 diagnostic code remains active. Proceed to test step 2.
NOT OK - The CID 0429 FMI 04 diagnostic code is no longer active. The sensor has failed.Repair: Replace the sensor. Verify that the new sensor corrects the problem.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 J1 machine harness connector from the ECM.
At the J1 machine harness connector, measure the resistance from contact J1-36 (wire N931-GY(Grey)) to ground.Expected Result:The resistance is greater than 5000 ohms.Results:
OK - The resistance is greater than 5000 ohms. The Implement ECM may have failed.Repair: The failed condition of the ECM is unlikely. Recheck the status of the diagnostic code. If the diagnostic code remains present, exit this procedure