416E, 420E and 430E Backhoe Loaders MID 039 - CID 1251 - FMI 03 Caterpillar

Conditions Which Generate This Code:

Illustration 1	g02103502
Schematic of the "Alternator W" Terminal

This diagnostic code is associated with the alternator. The FMI 03 diagnostic code means that the ECM has determined that the voltage of the circuit is above normal.

The possible causes of the diagnostic code are listed below:

• The alternator has failed.

• The energize circuit of the alternator is shorted to the +battery circuit.

• The ECM has failed. This 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 1251 FMI 03 is active before performing this procedure.

Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.

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 clean, that all connections are secure and that all connections are in good condition. If a problem with a connection is found, correct the problem and verify that this diagnostic code is active before performing this procedure.

System Response:

The diagnostic code of CID 1251 FMI 03 will be logged in the internal memory of the Machine ECM.

Test Step 1. CHECK FOR POWER.

1. Do not disconnect the harness connector from the alternator.

2. At the back of the harness connector for the alternator, insert a 7X-1710 Multimeter Probe along contact W (wire 450-YL) for the voltage supply.

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

4. Measure the voltage from contact W (wire 450-YL) to ground (wire 202-BK).

Expected Result:

The voltage is 10 DCV.

Results:

• OK - The voltage is 10 DCV. Proceed to Test Step 3.

• NOT OK - The voltage is not 10 DCV. The circuit is open.

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

  STOP

Test Step 2. CHECK THE SIGNAL CIRCUIT AT THE ALTERNATOR.

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

2. At the back of the harness connector for the alternator, remove the 7X-1710 Multimeter Probe from contact 1 and insert the probe along the signal wire (contact W).

3. At the back of the harness connector for the alternator, insert the 7X-1710 Multimeter Probe along the ground wire.

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

5. Monitor the signal of the sensor with the 146-4080 Digital Multimeter .

6. Without disconnecting the alternator or the hardware that is associated with the alternator from the machine, take the alternator through the full operating range.

Expected Result:

The alternator's signal responds in the manner that is described at the beginning of this procedure.

Results:

• OK - The alternator's signal responds correctly. The alternator is operating correctly. Proceed to Test Step 3.

• NOT OK - The alternator's signal does not respond correctly. The alternator is NOT operating correctly.

  Repair: Replace the alternator.

  STOP

Test Step 3. CHECK THE SIGNAL CIRCUIT AT THE ECM.

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

2. Insert the 7X-1710 Multimeter Probes into the back of the ECM connector along J2-14 (wire 450-YL) and J1-57 (wire 202-BK).

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

4. Monitor the signal of the alternator with the 146-4080 Digital Multimeter .

5. Without disconnecting the sensor or the hardware that is associated with the sensor from the machine, take the sensor through the full operating range of the sensor.

Expected Result:

The sensor's signal responds in the manner that is described at the beginning of this procedure.

Results:

• OK - The sensor's signal responds correctly. The sensor is operating correctly. Proceed to Test Step 4.

• NOT OK - The sensor's signal does not respond correctly. The harness has failed.

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

2. Disconnect the machine harness connectors from the sensor and the ECM.

3. Measure the resistance between contact J2-14 (wire 450-YL) 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. Inspect the harness connectors and clean the contacts of the machine harness connectors.

2. Reconnect all harness connectors.

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

4. Operate the machine.

5. Check the status of the CID 1251 FMI 03 diagnostic code.

Expected Result:

The CID 1251 FMI 03 diagnostic code is not active.

Results:

• OK - The CID 1251 FMI 03 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. Resume normal operation.STOP

• NOT OK - The CID 1251 FMI 03 diagnostic code is active. The diagnostic code has not been corrected. The ECM may have failed.

  Repair: Prior to replacing an ECM, always contact your dealership's Technical Communicator for possible consultation with AVSpare. This consultation may greatly reduce repair time. If the ECM must be replaced, refer to Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP