14L Motor Grader Implement Electronic Control System Caterpillar

Illustration 1	g03170678
Connections of the left joystick steer sensors.

Three steer position sensors are required for correct operation of the steering control. The steer position sensors are located in the assembly of the left joystick. Each sensor provides an input signal to the Implement ECM and to the Transmission/Chassis ECM. The ECM expects the input signals from all three steer position sensors to closely match. The FMI 14 diagnostic code is activated when the following occurs:

• ECM determines that the PWM input signal from the number three steer position sensor does not match the PWM input signal from the other steer position sensors.

The number three steer position sensor receives power from the 8V power supply of the Implement ECM. The number three steer position sensor is internally connected to ground. Ground is supplied by the Transmission/Chassis ECM and the Implement ECM. The steer position sensors must lose both grounds in order to lose a ground connection. The illustration above indicates the power and ground connections for the number three steer position sensor.

Note: For a schematic of the internal power and ground assignments for each individual component in the left joystick, refer to the Systems Operation, "Features" section of this manual.

The steer position sensors are PWM sensors. The steer position sensors operate at a frequency of 500 ± 100 Hz. The steer position sensors send a PWM input signal to the Implement ECM and to the Transmission/Chassis ECM. Following is the variation in the duty cycle of the signal:

• When the lever is in the FULL LEFT position, the duty cycle will be approximately 10%.

• When the lever is in the FULL RIGHT position, the duty cycle will be approximately 90%.

• When the lever is in the CENTER position, the duty cycle will be approximately 50%.

The possible causes of this diagnostic code are listed below:

• The sensor has failed.

• The ECM has failed. This is unlikely.

Note: If a MID 027 CID 0041 diagnostic code for the 8V power supply has been activated by the Transmission/Chassis ECM (MID 027), correct the problem before proceeding with this procedure.

Note: The correct operating temperature range for the steer position sensors is −40 °C (−40.0 °F) to 75 °C (167.0 °F). Return the temperature in the cab to a normal temperature when the temperature in the cab is extreme and a diagnostic code becomes active. Returning the temperature in the cab to a normal temperature will keep the steer position sensors operating in the acceptable temperature range. After returning the temperature to normal, verify that the CID 1473 FMI 14 diagnostic code is active before performing this procedure.

Note: The Transmission/Chassis ECM (MID 027) and the Implement ECM (MID 082) receive an input signal from the number three steer position sensor. Both electronic control modules can activate a CID 1473 FMI 14 diagnostic code when the following occurs: The signal from the number three steer position sensor does not match the signal from the other steer position sensors. If one of the electronic control modules has activated a CID 1473 FMI 14 diagnostic code and the other ECM has not activated a CID 1473 FMI 14 diagnostic code, it is likely that the sensor is operating correctly. When this occurs, a poor connection in the machine harness would be suspected. When both electronic control modules have activated the diagnostic code, either the sensor or a harness problem could be the cause. If both electronic control modules have activated the diagnostic code, it is unlikely that either ECM is causing the problem. For either condition, proceed with this procedure in order to verify the cause of the problem.

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 in good condition. The connections must be clean and the connections must be secure. 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 the diagnostic codes when the problem has been corrected.

Note: The next two test steps will measure the duty cycle of each steer position sensor in order to determine if one signal is not closely matching with both of the other sensor signals. Record the duty cycle of each of the three steer position sensors for comparison.

Test Step 1. CHECK THE SIGNAL AT THE NUMBER ONE STEER POSITION SENSOR

1. Turn the key start switch to the OFF position.

2. Turn the disconnect switch to the OFF position.

3. Do not disconnect the harness connector from the sensor.

4. Perform the following on the back of the joystick at connector J1. Insert 7X-1710 Multimeter Probes along each sensor signal contact and the return contact at J1-4.

5. Turn the disconnect switch and the key start switch to the ON position.

6. Move the joystick to the position that activates the code.

7. Hold the joystick in the position that activates the code.

8. Monitor the signal of the sensor with a digital multimeter.

9. Record the duty cycle of all the steer position sensors.

10. Compare the duty cycles of all three steer position sensors at the same specific position of the joystick.

Expected Result:

Each duty cycle is within 5% or less of the signals from the other sensors.

Results:

• OK. - There is 5% or less deviation in the duty cycle between the three steer position sensors with the joystick in the same position. Proceed to Test Step2.

• NOT OK. - With the joystick in the same position, one or more of the duty cycles deviates more than 5% from the other duty cycles. There is a problem with a steer position sensor.

  Repair: One of the steer position sensors is not operating correctly. Replace the assembly of the left joystick. After replacement of the assembly, verify that the new assembly is working correctly before operating the machine.

  STOP

Test Step 2. CHECK THE STATUS OF THE DIAGNOSTIC CODE

1. Inspect the harness connectors. Perform the following:

   • Clean the contacts of the harness connectors.

   • Check the wires for damage to the insulation that is caused by excessive heat, battery acid, or chafing.

2. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the sensor circuit.

3. Reconnect all harness connectors. Verify the following:

   • The connectors are fully seated.

   • The clips for each connector are completely fastened.

4. Operate the machine.

5. Check the status of the CID 1473 FMI 14 diagnostic code.

Expected Result:

The CID 1473 FMI 14 diagnostic code is not active.

Results:

• OK. - The CID 1473 FMI 14 diagnostic code is not active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor connection or a short at one of the connectors that was disconnected and reconnected. Clear logged codes. Verify that the assembly is working correctly. Resume normal operation.

  STOP

• NOT OK. - The CID 1473 FMI 14 diagnostic code is active. The diagnostic code has not been corrected.

  Repair: If the cause of the active diagnostic code is not found, the ECM that has activated this diagnostic code may have failed.

  If both the Transmission/Chassis ECM and the Implement ECM have activated this diagnostic code, it is unlikely that either ECM is causing the problem.

  Exit this procedure and perform this procedure again. If the cause of the failure is not found, contact the Technical Communicator of your dealership for possible consultation with Caterpillar. This consultation may greatly reduce repair time.

  If the ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP