VALVE GP-MODULATING 1864126 - Caterpillar

Illustration 1 g01640175
Schematic of the steering position sensor 1
The CID 1471 diagnostic code is associated with the steering position sensor 1. The FMI 12 means that the Power Train ECM has determined that the signal frequency of the steer position sensor 1 is not within the expected range.Multiple position sensors are required for correct operation of the steering control. Each sensor provides an input signal to the ECM that indicates the position of the steering control handle. The signal 1 receives power from the 8 VDC power supply circuit and the 8 VDC return circuit from the ECM. The position sensor sends a PWM input signal to the Power Train ECM.The position sensor is a PWM sensor that operates at a frequency of approximately 500 80 Hz. The voltage of the signal range is from 0 to 5 VDC. The duty cycle of the signal varies from approximately 10 percent at the full forward position to approximately 90 percent at the full rearward position. When the steering control handle is at the center position, the duty cycle is approximately 50% and the voltage is approximately 2.5 VDC. The possible causes of this diagnostic code are listed below:
The sensor has failed.
The ECM has failed. This condition 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.Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.Test Step 1. INSPECT THE SENSOR
Perform a visual inspection of the sensor, the wiring for the sensor and the hardware that is associated with the sensor. Expected Result:There is no apparent damage to the sensor, the wiring for the sensor or the hardware that is associated with the sensor.Results:
OK - There is no apparent damage to the sensor, the wiring for the sensor or the hardware that is associated with the sensor. Proceed to Test Step 2.
NOT OK - There is apparent damage to the sensor, the wiring for the sensor or the hardware that is associated with the sensor.Repair: Replace the damaged part.Proceed to Test Step 4.Test Step 2. CHECK THE SIGNAL OF THE SENSOR
Turn the key start switch and the disconnect switch to the OFF position.
At the back of the harness connector for the sensor, insert the 7X-1710 Multimeter Probe along contact 2 (wire J766-PU(Purple)).
At the back of the harness connector for the sensor, insert the other 7X-1710 Multimeter Probe along contact 3 (wire 828-WH(White)).
Turn the disconnect switch and the key start switch to the ON position.
Monitor the frequency of the sensor with the 146-4080 Digital Multimeter.
Without disconnecting the sensor or hardware associated with the sensor from the machine, take the sensor through the full operating range. Expected Result:The frequency of the signal drops below 380 Hz.Results:
OK - The frequency of the signal drops below 380 Hz. The sensor has failed.Repair: Replace the sensors.STOP
NOT OK - The sensor signal remains above 380 Hz. Proceed to Test Step 3.Test