ELBOW 0038152 - Caterpillar

Illustration 1 g02140583
Connections of the Steering Position Sensor #3
This diagnostic code is associated with steering position sensor 3. The FMI 03 diagnostic code is activated when the ECM reads the voltage of the input signal above the acceptable 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 3 receives power from the 10 VDC power supply circuit and the 10 VDC return circuit from the ECM. The position sensor sends a PWM input signal to the 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 left position to approximately 90 percent at the full right 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:
The power supply circuit is open.
The return circuit is open.
The signal circuit is open.
The signal circuit is shorted to another voltage source.
The sensor has failed.
The ECM has failed. An ECM failure is unlikely. Check for an active MID 113 - CID 1482 - FMI 03 diagnostic code. A problem with the 10 VDC supply can cause this diagnostic code to be active. Perform the MID 113 - CID 1482 - FMI 03 troubleshooting procedure and clear the diagnostic code before performing 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. Verify that all connections in the circuit are clean, that all connections are secure and that all connections are in good condition. 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 these diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 1473 - FMI 03 is active before performing this procedure.Note: Use a digital multimeter for the measurements in this procedure.Test Step 1. Check the power supply circuit to the sensor
Turn the disconnect switch and the key start switch to the ON position. Do not start the engine.
At the machine harness side of the steering control connector, insert a multimeter probe along contact "12" wire (U727-YL(Yellow)) and along contact "11" wire (J765-BU(Blue)). Do not disconnect the machine harness connector from the sensor.
Measure the voltage. Expected Result:The voltage measurement is between 9 and 11 VDC.Results:
YES - The voltage measurement is between 9 and 11 VDC. The power circuits for the sensor are correct. Proceed to Test Step 2.
NO - The voltage measurement is less than