D6N Track-Type Tractor Caterpillar

Illustration 1	g01757493

Illustration 2	g01891535
Location of the transmission output speed sensors

A CID 0673 is associated with the Transmission Speed sensor #2. An FMI 02 means the machine ECM is receiving erratic, intermittent, or incorrect data from the sensor.

Note: A CID 0673 is activated when the ECM compares the Transmission Speed sensor #2 signal to the Transmission Speed sensor #1 signal. The ECM will issue a CID 0673 diagnostic code if the data from the sensors is not within certain parameters. Both transmission speed sensors have a "fixed-mount" arrangement. When the sensor is mounted securely, no further adjustments are necessary.

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: Check the Transmission Speed sensor mounting, before performing the following procedure. If the speed sensor is mounted securely, and CID 0673 FMI 02 code is active, go to Test Step 1.

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 E907-GY), and then from contact 2 (wire E906-OR), 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 sensor has failed.

  Repair: Replace the sensor.

  Go to Test Step 5

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 E907-GY to the contact for wire E906-OR.

Expected Result:

Resistance is between 600 to 1800 ohms.

Results:

• YES - The resistance is within the acceptable range. The sensor has not failed. Go to Test Step 3.

• NO - The resistance is NOT within an acceptable range. The speed sensor has failed.

  Repair: Replace the speed sensor.

  Go to Test Step 5

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 E907-GY to the contact for wire E906-OR.

5. At the J1 ECM harness connector, measure the resistance between contact J1-4 (wire E906-OR) and contact J1-5 (wire E907-GY).

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: Repair or replace the harness.

  Go to Test Step 5

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

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

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

3. At the machine harness connector for the ECM, measure the resistance between contacts J1-4 (wire E906-OR) to all other contacts in the ECM connector. Then, measure resistance from contact J1-5 (E907-GY) 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 is less than 5000 ohms. There is a short circuit in the harness.

  Repair: The short is form wire E906-OR, or from wire E906-OR, to the wire with the low resistance. Repair or replace the harness.

  STOP

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 0673 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.

  STOP

• 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 5 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".

  STOP