Air Conditioning and Heating R134a for All Caterpillar Machines – MID 113 – CID 1472 – FMI 03

Conditions Which Generate This Code:



Illustration 1 g02154879

Schematic of the steering position sensor 2

The CID 1472 diagnostic code is associated with the steering position sensor 2. The FMI 03 diagnostic code is activated when the ECM reads the voltage of the input signal from the sensor 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 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 power supply circuit is open.

  • The return circuit is open.

  • The signal circuit is shorted to another voltage source.

  • The sensor has failed.

  • The ECM has failed. This condition is unlikely.

Check for an active MID 113 CID 0041 FMI 03 diagnostic code. A problem with the 8 VDC supply may cause this diagnostic code to be active. If the diagnostic code is active, perform the MID 113 CID 0041 FMI 03 procedure. 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 CID 1472 FMI 03 diagnostic code is active before performing this procedure.

Note: Use a digital multimeter for the measurements in this procedure.

Test Step 1. CHECK THE SENSOR POWER SUPPLY

  1. Turn the disconnect switch and the key start switch to the ON position. Do not start the engine.
  1. At the machine harness connector for the sensor, insert a multimeter probe along contact 4 C985-BU and along contact 5 J766-PU. Do not disconnect the machine harness connector from the sensor.
  1. Measure the voltage.

Expected Result:

The voltage measurement is between 7 and 9 VDC.

Results:

  • OK – The voltage measurement is between 7 and 9 VDC. The power circuits for the sensor are correct. Proceed to Test Step 2.

  • NOT OK – The voltage measurement is less than 7 VDC. The power supply for the sensor is not correct. There is an open circuit or a bad connection in the machine harness. The problem is in C985-BU.

    Repair: Refer to Electrical System Schematic, Electrical Schematic, KENR8935. Examine all of the connectors that are in the circuit. Ensure that the connections are clean and secure. Repair the machine harness or replace the machine harness. Refer Troubleshooting, “MID 113 – CID 0041 – FMI 03” for more information on troubleshooting the 8 VDC power supply to the sensor. The 8 VDC power supply from the ECM also supplies power for steering position sensor 2. If a CID 1472 diagnostic code is not active, the most likely problem is in the supply circuit or return circuit for position sensor 2. Check these circuits individually to isolate the problem. Once the power supply has been corrected, verify that the CID 1472 FMI 03 diagnostic code is no longer active.

    STOP

Test Step 2. CHECK FOR AN OPEN IN THE SENSOR CIRCUIT

  1. Turn the key start switch and the disconnect switch to the OFF position.
  1. Disconnect the steering control connector from the speed/direction handle. At the harness connector for the sensor, place a jumper wire between contact 5 J766-PU and the contact 6 829-GN.
  1. Disconnect the J1 and J2 machine harness connectors from the ECM.
  1. At the machine harness connectors for the ECM, measure the resistance between contact J1-45 J766-PU and contact J2-25 829-GN.
  1. Wiggle the connectors for the ECM and the connector for the sensor while you observe the resistance measurement. Do not disconnect the jumper wire.

Expected Result:

The resistance measurement is less than 5 ohms.

Results:

  • OK – The resistance measurement is less than 5 ohms. The circuit is correct. Proceed to Test Step 3

  • NOT OK – The resistance measurement is greater than 5 ohms. There is an open or a bad connection in the circuit. The problem is with 829-GN.

    Repair: Refer to Electrical Schematic, KENR8935. Examine all of the connectors that are in the circuit. Ensure that the connections are clean and secure. Repair the machine harness or replace the machine harness.

    STOP

Test Step 3. CHECK THE SIGNAL CIRCUIT FOR A SHORT

The key start switch and the disconnect switch remain in the OFF position. The machine harness connectors remain disconnected from the sensor and the ECM.

  1. Remove the jumper wire that was installed in the last step.
  1. At the J2 machine harness connector for the ECM, measure the resistance from the contact J2-25 829-GN to all of the other J1 and J2 contacts that are used for the ECM.

Expected Result:

Each resistance measurement is greater than 5000 ohms.

Results:

  • OK – Each resistance measurement is greater than 5000 ohms. The circuits are correct. Proceed to Test Step 4

  • NOT OK – A resistance measurement is less than 5000 ohms. There is a short in the machine harness. The short is between 829-GN and the circuit with the low resistance measurement.

    Repair: Refer to Electrical Schematic, KENR8935. Examine all of the connectors that are in the circuit. Ensure that the connections are clean and secure. Repair the machine harness or replace the machine harness.

    STOP

Test Step 4. CHECK THE SIGNAL AT THE SENSOR

The sensor remains disconnected from the machine harness connector. The disconnect switch and the key start switch remain in the OFF position. The machine harness connectors remain disconnected from the ECM.

  1. At the steering control connector, use a wire removal tool to remove the 829-GN and the socket at contact 6 from the harness connector.
  1. Reconnect the machine harness connector to the sensor.
  1. Reconnect the J1 and J2 machine harness connectors to the ECM.
  1. Turn the disconnect switch and the key start switch to the ON position. Do not start the engine.
  1. At the back of the connector for the sensor, insert the multimeter probes along contact 5 and contact 6 for the sensor. Ensure that a good connection is made between the probes and the connector contacts.
  1. Measure the frequency, the duty cycle, and the voltage of the signal. Move the steering control handle through the full range of the motion that is described at the beginning of this procedure.

Expected Result:

The frequency. the duty cycle, and the voltage are correct according to the description at the beginning of this procedure.

Results:

  • OK – The frequency, the duty cycle, and the voltage are correct. The sensor is not the cause of the problem. Install 829-GN and the socket back to the original location in the machine harness connector for the sensor. Verify that all of the wires are secure in the correct locations before proceeding to the next step. Proceed to Test Step 5.

  • NOT OK – The frequency, the duty cycle, or the voltage is not correct according to the description at the beginning of this procedure. If any one of the values are not within the acceptable range, the sensor has failed.

    Repair: Repair: Perform this procedure again to verify that the signal is not correct. Replace the sensor group if the signal is not correct. Calibrate the sensor after the sensor is replaced. Refer to Testing and Adjusting, “Calibration”.

    STOP

Test Step 5. CHECK THE STATUS OF THE DIAGNOSTIC CODE

  1. Clean the contacts of the harness connectors.
  1. Reconnect all harness connectors.
  1. Turn the key start switch to the ON position.
  1. Operate the machine.
  1. Determine if the CID 1472 FMI 03 diagnostic code is present.

Expected Result:

The CID 1472 FMI 03 diagnostic code is Not active.

Results:

  • OK – The CID 1472 FMI 03 diagnostic code is not active. The diagnostic code does not exist at this time. The initial diagnostic code may have been caused by a poor electrical connection that was corrected when a harness connector was disconnected and reconnected.

    Repair: Resume normal operation.

    STOP

  • NOT OK – The CID 1472 FMI 03 diagnostic code is active. The diagnostic code has not been corrected.

    Repair: With Caterpillar Electronic Technician (Cat ET), if available, perform a “Wiggle Test” on the steering position sensor 2 circuit in the machine wiring harness. The wiggle test may detect momentary or intermittent shorts or opens in the machine wiring harness.If all possible causes of the problem have been investigated and no problem can be found, you may need to replace the Power Train ECM.Prior to replacing an ECM, always contact the Technical Communicator at your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time and expense. If the ECM must be replaced, refer to Testing and Adjusting, “Electronic Control Module (ECM) – Replace”.

    STOP

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