D6N Track-Type Tractor Caterpillar

Illustration 1	g01741535
Cab Ventilation Duct Temperature sensor schematic

A CID 2663 is associated with the Cab Ventilation Duct Temperature sensor. An FMI 03 indicates the machine ECM has found the sensor circuit voltage above normal.

Possible causes for this diagnostic code are:

• Failed sensor.

• Open sensor circuit.

• Sensor output circuit shorted to +DCV supply.

• 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 2663 FMI 03 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.

System Response:

A level 1 warning will be generated.

Note: Ensure that CID 2663 FMI 03 is active. This procedure can cause new diagnostic codes to be recorded. Ignore these created diagnostic codes. When the procedure is completed, clear the created diagnostic codes.

Test Step 1. CHECK THE SENSOR, ECM, AND HARNESS

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

2. Disconnect the harness connector from the Cab Ventilation Duct Temperature sensor.

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

4. Observe the status of the CID 2663 FMI 03 diagnostic code.

Expected Result:

The diagnostic code stays active and does not change.

Results:

• YES - The diagnostic code remains active and does not change. The sensor is not the problem. Go to Test Step 2.

• NO - The diagnostic code is no longer active, and has changed into an active CID 2663 FMI 04 diagnostic code. The sensor has failed.

  Repair: Replace the sensor.

  Go to Test Step 4.

Test Step 2. CHECK THE SENSOR FOR AN OPEN CIRCUIT

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

2. The sensor remains disconnected from the harness connector.

3. At the sensor harness connector, place a jumper wire from the contact for wire J767-GY, to the contact for wire E558-YL in the connector.

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

5. At the J1 ECM harness connector, measure the resistance from contact J1-21 (wire J767-GY) to contact J1-29 (wire E558-YL).

Expected Result:

The resistance measurement is less than 5 ohms.

Results:

• YES - The resistance measurement is less than 5 ohms. There are no open circuits in the harness. Go to Test Step 3.

• NO - The resistance measurement is greater than 5000 ohms.

  Repair: There is an open circuit in the machine harness. The open is in wire J767-GYor in wire E558-YL. Repair or replace the harness.

  Go to Test Step 4.

Test Step 3. CHECK THE SENSOR CIRCUIT FOR A +VDC SHORT

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

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

3. The J1 ECM harness connector remains disconnected.

4. Disconnect the J2 harness connector from the machine ECM also.

5. At the J1 ECM harness connector, measure resistance from contact J1-29 (wire E558-YL) to all of the other contacts used in both the J1 and J2 ECM harness connectors.

Expected Result:

Each resistance measurement is greater than 5000 ohms.

Results:

• YES - Each resistance measurement is greater than 5000 ohms. There are no short circuits in the harness. Go to Test Step 4.

• NO - One or more resistance measurements are less than 5 ohms.

  Repair: There is a short circuit in the harness. The short circuit is from wire E558-YL to the wire with the low resistance measurement. Repair or replace the harness.

  Go to Test Step 4.

Test Step 4. 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 0600 FMI 03 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 4 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