D6N Track-Type Tractor Caterpillar

Illustration 1	g02730430
Connections of the power train speed range control position sensor.

This diagnostic code is associated with the power train speed range control position sensor. This sensor produces a square wave output. The FMI 08 means that the ECM has determined that the signal frequency or the signal pulse width is not within the expected range.

Note: The diagnostic code will not be cleared until the machine has been driven.

The possible causes of this diagnostic code are listed below:

• The supply voltage has failed

• The sensor has failed.

• Intermittent connections or poor connections

• 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 these diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 2500 FMI 08 is active before performing this procedure.

Note: Use a digital multimeter that has been calibrated for the measurements in this procedure.

Test Step 1. CHECK THE VOLTAGE AT THE SENSOR

1. Disconnect the machine harness from the sensor.

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

3. At the machine harness connector for the sensor, measure the voltage between contact 1 (wire 709-OR) and frame ground.

Expected Result:

The voltage is 10± 0.5 VDC.

Results:

• OK - The voltage is 10± 0.5 VDC. Proceed to Test Step 4.

• NOT OK - The voltage is NOT 10± 0.5 VDC. Proceed to Test Step 2.

Test Step 2. INSPECT THE HARNESS CONNECTIONS

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

2. Inspect all harness connections that are related to the sensor. Ensure that the connectors are clean and tight.

3. Check the connectors for proper mating. Ensure that all the seals are present and in place.

4. Check the harness for signs of damage or abrasion.

5. Check the wires at the connector. Ensure that the wires are secured tightly into the connector.

6. Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit. Take care not to pull the wire out of the connector.

7. Check the exposed wires at the connectors for nicks or signs of abrasion.

8. Check for moisture inside the connector.

9. Check the connectors for dirty contacts or corroded contacts.

10. Check each pin and each socket of the machine harness connectors. Ensure that the contacts are properly installed. The contacts should mate correctly when the two pieces of the connector are placed together.

Expected Result:

The machine harness connectors are tight and free of corrosion.

Results:

• OK - The machine harness connectors are tight and free of corrosion. Proceed to Test Step 3.

• NOT OK - The machine harness connectors are in need of repair.

  Repair: Repair the machine harness or replace the machine harness.

  STOP

Test Step 3. CHECK THE CIRCUIT FOR AN OPEN

1. The disconnect switch and the key start switch remain in the OFF position.

2. Disconnect the machine harness from the sensor.

3. Disconnect the machine harness connector J2 from the ECM.

4. At the J2 machine harness connector for the ECM, measure the resistance from contact J2-16 for the sensor to frame ground.

Expected Result:

The resistance is less than 5.0 ohms.

Results:

• OK - The resistance is less than 5.0 ohms. The sensor circuit is operating correctly. Proceed to Test Step 4.

• NOT OK - The resistance is greater than 5000 ohms. There is an open circuit in the machine harness.

  Repair: Repair the machine harness or replace the machine harness.

  STOP

Test Step 4. CHECK THE SIGNAL CIRCUIT FOR A SHORT IN THE HARNESS

1. The disconnect switch and the key start switch remain in the OFF position.

2. The harness connectors remain disconnected from the sensor and the ECM.

3. Measure the resistance between contact J2-16 (wire J883-BU) and all contacts that are used in the machine harness connectors for the ECM.

Expected Result:

The resistance is greater than 5000 ohms.

Results:

• OK - The resistance is greater than 5000 ohms. The circuit is correct. Proceed to Test Step 5.

• NOT OK - The resistance is less than 5 ohms. The signal circuit is shorted to another circuit in the harness.

  Repair: Repair the machine harness or replace the machine harness.

  STOP

Test Step 5. CHECK IF THE DIAGNOSTIC CODE REMAINS

1. Reconnect all harness connectors. Ensure that the connectors are fully seated.

2. Ensure that the clips for each connector are fastened.

3. Turn the battery disconnect switch and the key start switch to the ON position.

4. Operate the machine.

5. Drive the machine.

6. Determine if the diagnostic code is active.

Expected Result:

The diagnostic code is no longer active.

Results:

• OK - The CID 2500 FMI 08 diagnostic code is not active. The problem does not exist at this time. The initial diagnostic code may have been caused by a connector problem.

  Repair: Resume normal machine operation.

  STOP

• NOT OK - The CID 2500 FMI 08 diagnostic code is active. The problem has not been corrected.

  Repair: With Caterpillar Electronic Technician (Cat ET), if available, perform a "Wiggle Test" on the transmission output speed sensor 1 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 Transmission ECM.Prior to replacing an ECM, contact the Technical Communicator at your dealership for a 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