Air Conditioning and Heating R134a for All Caterpillar Machines – MID 113 – CID 1473 – FMI 04

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 04 diagnostic code is activated when the Power Train ECM detects the voltage of the input signal is below 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 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 here:

  • The sender has failed.

  • The signal circuit in the machine harness is shorted to ground.

  • The ECM has failed. This condition is unlikely.

Check for an active MID 113 CID 0041 FMI 04 diagnostic code. A problem with the 10 VDC supply may cause this diagnostic code to be active. If the diagnostic code is active, perform the MID 113 CID 0041 FMI 04 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 1473 FMI 04 diagnostic code is active before performing this procedure.

Test Step 1. CHECK THE SENSOR

  1. Turn the disconnect switch and the key start switch to the ON position. Do not start the engine.
  1. Disconnect the machine harness connector from the sensor. Observe the status of the active FMI 04 diagnostic code.

Expected Result:

The FMI 04 diagnostic code remains active when the harness connector is disconnected. An FMI 03 diagnostic code has not been activated by the ECM.

Results:

  • OK – The FMI 04 diagnostic code remains active when the harness connector is disconnected. The sensor is not causing the problem. Proceed to test step 2.

  • NOT OK – The FMI 04 diagnostic code is no longer active when the harness connector is disconnected from the sensor. An FMI 03 diagnostic code is activated when the harness connector is disconnected. The machine harness and the ECM are operating correctly. The sensor is causing the problem. There is an internal short to ground in the sensor group.

    Repair: Replace the sensor group. Calibrate the sensor after the sensor is replaced. Refer to Testing and Adjusting, “Calibration”.Verify that the new sensor has corrected the problem.

    STOP

Test Step 2. 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 J2-26 830-OR 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 3

  • NOT OK – A resistance measurement is less than 5000 ohms. There is a short in the machine harness. The short is between 830-OR 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 3. 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 1473 FMI 04 diagnostic code is present.

Expected Result:

The CID 1473 FMI 04 diagnostic code is Not active.

Results:

  • OK – The CID 1473 FMI 04 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 1473 FMI 04 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 3 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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