D6N Track-Type Tractor Caterpillar

Illustration 1	g01878715
Schematic of the Torque Converter Speed Sensor

A CID 0672 is associated with the Torque Converter speed sensor. An FMI 02 means the Engine ECM is receiving erratic, intermittent, or incorrect data from the sensor.

Possible causes for this diagnostic code are:

• Speed sensor failure.

• Speed sensor circuit is open.

• Speed sensor circuit is shorted.

• Machine ECM failure, but is most unlikely.

Note: Poor connections often cause problems in electrical circuits. Before performing this procedure, inspect all of the harness connectors involved in the circuit. Verify that all circuit connections are clean, secure, and in good condition. If a problem is found with any of the connections: correct the problem, and verify that diagnostic code CID 0672 FMI 02 is still active, before performing the following procedures.

Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes now, but clear those codes after the original diagnostic code has been corrected.

Test Step 1. CHECK SENSOR TO CASE RESISTANCE.

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

2. Disconnect the machine harness connector from the sensor.

3. At the sensor, measure resistance first from contact 1 (wire E909-WH), and then from contact 2 (wire E908-BR), to the sensor case.

Expected Result:

Resistance is more than 10,000 ohms.

Results:

• YES - The resistance is more than 10,000 ohms. Go to Test Step 2.

• NO - The resistance is less than 10,000 ohms. The speed sensor has failed.

  Repair: Replace the sensor.

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Test Step 2. CHECK SENSOR RESISTANCE.

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

2. The harness connector remains disconnected from the sensor.

3. At the sensor harness connector, measure resistance between the contact for wire E908-BR to the contact for wire E909-WH.

Expected Result:

The resistance is approximately 1100 ohms.

Results:

• YES - The resistance is approximately 1100 ohms. The sensor resistance is correct. Go to Test Step 3.

• NO - The resistance is not approximately 1100 ohms. The sensor has failed.

  Repair: Replace the sensor.

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Test Step 3. CHECK THE SENSOR CIRCUITS FOR AN OPEN.

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

2. The harness connector remains disconnected from the sensor.

3. Disconnect the J1 harness connector from the machine ECM.

4. At the sensor harness connector, place a jumper wire from the contact for wire E908-BR to the contact for wire E909-WH.

5. At the ECM J1 harness connector, measure the resistance from contact J1-15 (wire E908-BR) to contact J1-16 (wire E909-WH).

Expected Result:

The resistance is less than 5 ohms.

Results:

• YES - The resistance is less than 5 ohms. There are no open circuits in the harness. Go to Test Step 4.

• NO - The resistance is more than 5 ohms. There is an open circuit in the harness.

  Repair: The open is in wire E908-BR, or in wire E909-WH. Repair or replace the harness.

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Test Step 4. CHECK THE SENSOR CIRCUITS FOR A SHORT.

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

2. The harness connector remains disconnected from the sensor, but the jumper wire is removed.

3. At the J1 harness connector, measure resistance from contact J1-15 to all other contacts used in the ECM J1 harness connector. Then, measure resistance from contact J1-16 to all other contacts used in the J1 harness connector.

Expected Result:

Each resistance is more than 5000 ohms.

Results:

• YES - Each resistance is more than 5000 ohms. There are no short circuits in the harness. Go to Test Step 5.

• NO - A resistance measured more than 5000 ohms. There is a short circuit in the harness.

  Repair: The short is form wire E909-WH, or from wire E908-BR, to the wire with the low resistance. Repair or replace the harness.

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Test Step 5. CHECK THE DIAGNOSTIC CODE STATUS.

1. Reconnect all disconnected machine harness connectors. Make sure that all the connectors are clean, and fully seated. Observe that the clips for each connector are securely fastened.

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

3. Clear all inactive diagnostic codes.

4. Operate the machine.

5. Check the status of the CID 0672 FMI 02 diagnostic code.

Expected Result:

The diagnostic code is not active.

Results:

• YES - The diagnostic code is no longer active and does not exist at this time.

  Repair: Return machine to normal operation.

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• NO - The diagnostic code is still active. The problem has not been corrected. The ECM may have failed.

  Repair: If you have not inspected the harness connectors in a previous Test Step, do that now. Clean the contacts of the harness connectors. Check the wires for damage to the insulation caused by excessive heat, battery acid, or chafing.Perform a 45 N (10 lb.) pull test on each of the wires that are associated with the sensor circuit.Perform a "wiggle test" on the sensor circuit of the machine wiring harness, using the Caterpillar Electronic Technician service tool. The "wiggle test" can be used to detect open or shorted connections in the machine wiring harness.Reconnect all harness connectors. Make sure that the connectors are fully seated. Observe that the clips for each connector are fastened. Perform Test Step 6 again. If the problem was again not found, and the original code is still active, the machine ECM may have failed.Prior to replacing an ECM, always contact your Dealership Technical Communicator for possible consultation with Caterpillar, or with the Dealer Solutions Network. This consultation may greatly reduce repair time. If the ECM needs to be replaced, see Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

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