Air Conditioning and Heating R134a for All Caterpillar Machines – MID 113 – CID 1473 – FMI 12

Conditions Which Generate This Code:



Illustration 1 g02140583

Connections of the Steering Position Sensor 3

The CID 1473 diagnostic code is associated with the steering position sensor 3. The FMI 12 means that that the Power Train ECM has determined that the signal frequency of the Steer Position Sensor 3is 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 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 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.

  1. 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

  1. Turn the key start switch and the disconnect switch to the OFF position.
  1. At the back of the harness connector for the sensor, insert the 7X-1710 Multimeter Probe along contact 5 (wire J765-BU).
  1. At the back of the harness connector for the sensor, insert the other 7X-1710 Multimeter Probe along contact 11 (wire 830-OR).
  1. Turn the disconnect switch and the key start switch to the ON position.
  1. Monitor the frequency of the sensor with the 146-4080 Digital Multimeter .
  1. 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.

    Repair: The sensor has failed. Replace the sensors.

    STOP

  • NOT OK – The sensor signal remains above 380 Hz. Proceed to Test Step 3.

Test Step 3. CHECK THE SIGNAL AT THE POWER TRAIN ECM

  1. Turn the key start switch and the disconnect switch to the OFF position.
  1. Insert the 7X-1710 Multimeter Probes into the back of the ECM connector along J2-26 (wire 830-OR) and J1-56 (wire J765-BU).
  1. Turn the disconnect switch and the key start switch to the ON position.
  1. Monitor the signal of the sensor with the 146-4080 Digital Multimeter .
  1. 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.

    Repair: Check the signal at the sensor again. The machine harness is not likely to cause the frequency to change. Repair the machine harness or replace the machine harness.

    STOP

  • NOT OK – The sensor signal remains above 380 Hz. Proceed to Test Step 4.

Test Step 4. CHECK THE ADJUSTMENT AND/OR THE CALIBRATION OF THE SENSOR.

  1. Turn the disconnect switch and the key start switch to the ON position.
  1. Perform the adjustment procedure for the position sensor, if necessary. Then perform the calibration of the position sensor. Refer to the Testing and Adjusting section of the manual for additional information on these procedures.
  1. Without disconnecting the sensor or the hardware that is associated with the sensor, move the sensor through the entire range of motion.

    Note: On some machines, you may need to start the engine to move the sensor through the entire range of motion.

  1. Check the status of the diagnostic code.

Expected Result:

The CID 1473 FMI 12 diagnostic code is not active.

Results:

  • OK – The diagnostic is not active. The adjustment and/or the calibration has corrected the failure.

    Repair: Resume normal operation.

    STOP

  • NOT OK – The CID 1473 FMI 12 diagnostic code is still active.

    Repair: Measure the duty cycle of the remaining position sensors. If the duty cycle of this sensor differs from the remaining sensors by more than 10%, replace the sensor.

    STOP

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