IT38G Series II Integrated Toolcarrier and 938G Series II Wheel Loader Caterpillar

Illustration 1	g00920589
Schematic for the Rotary Switch (Variable Shift Control)

This diagnostic code is associated with the Rotary Switch (Variable Shift Control). The rotary switch is connected to three inputs of the ECM. Two contacts are open and the other contact is grounded during proper operation.

This FMI 03 means that the ECM has determined that the normally open contacts and the normally closed contact are open.

Note: The following test procedure may create other diagnostic codes. Ignore these diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 1521 FMI 03 is active before performing this procedure.

Test Step 1. CHECK THE GROUND CIRCUIT OF THE SWITCH IN THE HARNESS

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

2. Disconnect the machine harness connector(s) from the ECM.

3. Measure the resistance between contact J1-16 (wire X962-OR) of the machine harness for the ECM and the contact 1 (wire X962-OR) .

Expected Result:

The resistance is less than 5 ohms.

Results:

• OK - The resistance is less than 5 ohms. The circuit is correct. Proceed to Test Step 2.

• NOT OK - The resistance is greater than 5000 ohms. The circuit is open. The machine harness has failed.

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

  Stop.

Test Step 2. CHECK THE SWITCH CIRCUITS FOR A SHORT TO THE +BATTERY CIRCUIT

1. The machine harness connector(s) remains disconnected from the ECM.

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

3. Disconnect the 6-pin connector for the switch from the machine harness.

4. At the machine harness connector for the ECM, measure the resistance from contact J1-24 (wire X973-BU), contact J1-20 (wire X974-BR), and contact J1-39 (wire X972-GN) of the machine harness to all the contacts that are used in the machine harness connectors for the ECM.

Expected Result:

Each resistance measurement is greater than 5000 ohms.

Results:

• OK - Each resistance measurement is greater than 5000 ohms. The harness is correct. Proceed to Test Step 3.

• NO - One or more of the measurements were less than 5 ohms. There is a short in the machine harness.

  Repair: The short is between wire X973-BU and the circuit with the lowest resistance measurement, wire X974-BR and the circuit with the lowest resistance measurement, or the short is between wire X972-GN and the circuit with the lowest resistance measurement. Repair the machine harness or replace the machine harness.

  Stop.

Test Step 3. CHECK THE SWITCH CIRCUITS IN THE HARNESS

1. The machine harness remains disconnected from the ECM and the switch.

2. At the harness connector for the switch, connect a jumper wire between contact 4 (wire X974-BR) and contact 3 (wire X973-BU).

3. At the harness connector for the ECM, measure the resistance from contact J1-20 (wire X974-BR) to contact J1-24 (wire X973-BU).

4. At the harness connector for the switch, connect a jumper wire between contact 2 (wire X972-GN) and contact 3 (wire X973-BU).

5. At the harness connector for the ECM, measure the resistance from contact J1-39 (wire X972-GN) to contact J1-24 (wire X973-BU).

Expected Result:

The resistance is less than 5 ohms.

Results:

• OK - The resistance is less than 5 ohms. Proceed to Test Step 4.

• NOT OK - The resistance is greater than 5000 ohms. The circuit is open.

  Repair: The machine harness has failed. Repair the machine harness or replace the machine harness.

  Stop.

Test Step 4. CHECK THE OPERATION OF THE SWITCH (POWER POSITION)

1. Remove the jumper that was installed in the previous Test Step.

2. The machine harness remains disconnected from the switch.

3. Rotate the switch to the power position.

4. Connect one lead from a multimeter to contact 1 (wire X962-OR) of the harness connector for the switch.

5. Connect the other lead from a multimeter to contact 2 (wire X972-GN) of the harness connector for the switch.

6. Measure the resistance between contact 1 (wire X962-OR) and contact 2 (wire X972-GN). Note the resistance.

7. Disconnect the lead from contact 2 (wire X972-GN) and connect the lead to contact 3 (wire X973-BU).

8. Measure the resistance between contact 1 (wire X962-OR) and contact 3 (wire X973-BU).

9. Disconnect the lead from contact 3 (wire X973-BU) and connect the lead to contact 4 (wire X974-BR).

10. Measure the resistance between contact 1 (wire X962-OR) and contact 4 (wire X974-BR).

Expected Result:

The resistance from contact 1 to contact 2 is less than 5 ohms, and the resistance from contact 1 to contacts 3 and 4 is greater than 5000 ohms.

Results:

• YES - The resistance from contact 1 to contact 2 is less than 5 ohms, and the resistance from contact 1 to contacts 3 and 4 is greater than 5000 ohms. The switch is operating correctly in the power position. Proceed to Test Step 5.

• NO - The resistance from contact 1 to contact 2 is not less than 5 ohms, or the resistance from contact 1 to contacts 3 and 4 is not greater than 5000 ohms. The switch has failed.

  Repair: Replace the switch.

  Stop.

Test Step 5. CHECK THE OPERATION OF THE SWITCH (MIDRANGE POSITION)

1. Rotate the switch to the midrange position.

2. Connect one lead from a multimeter to contact 1 (wire X962-OR) of the harness connector for the switch.

3. Connect the other lead from a multimeter to contact 2 (wire X972-GN) of the harness connector for the switch.

4. Measure the resistance between contact 1 (wire X962-OR) and contact 2 (wire X972-GN). Note the resistance.

5. Disconnect the lead from contact 2 (wire X972-GN) and connect the lead to contact 3 (wire X973-BU).

6. Measure the resistance between contact 1 (wire X962-OR) and contact 3 (wire X973-BU).

7. Disconnect the lead from contact 3 (wire X973-BU) and connect the lead to contact 4 (wire X974-BR).

8. Measure the resistance between contact 1 (wire X962-OR) and contact 4 (wire X974-BR).

Expected Result:

The resistance from contact 1 to contact 3 is less than 5 ohms, and the resistance from contact 1 to contacts 2 and 4 is greater than 5000 ohms.

Results:

• YES - The resistance from contact 1 to contact 3 is less than 5 ohms, and the resistance from contact 1 to contacts 2 and 4 is greater than 5000 ohms. The switch is operating correctly in the midrange position. Proceed to Test Step 6.

• NO - The resistance from contact 1 to contact 3 is not less than 5 ohms, or the resistance from contact 1 to contacts 2 and 4 is not greater than 5000 ohms. The switch has failed.

  Repair: Replace the switch.

  Stop.

Test Step 6. CHECK THE OPERATION OF THE SWITCH (ECONOMY POSITION)

1. Rotate the switch to the economy position.

2. Connect one lead from a multimeter to contact 1 (wire X962-OR) of the harness connector for the switch.

3. Connect the other lead from a multimeter to contact 2 (wire X972-GN) of the harness connector for the switch.

4. Measure the resistance between contact 1 (wire X962-OR) and contact 2 (wire X972-GN). Note the resistance.

5. Disconnect the lead from contact 2 (wire X972-GN) and connect the lead to contact 3 (wire X973-BU).

6. Measure the resistance between contact 1 (wire X962-OR) and contact 3 (wire X973-BU).

7. Disconnect the lead from contact 3 (wire X973-BU) and connect the lead to contact 4 (wire X974-BR).

8. Measure the resistance between contact 1 (wire X962-OR) and contact 4 (wire X974-BR).

Expected Result:

The resistance from contact 1 to contact 4 is less than 5 ohms, and the resistance from contact 1 to contacts 2 and 3 is greater than 5000 ohms.

Results:

• YES - The resistance from contact 1 to contact 4 is less than 5 ohms, and the resistance from contact 1 to contacts 2 and 3 is greater than 5000 ohms. The switch is operating correctly in the economy position. Proceed to Test Step 7.

• NO - The resistance from contact 1 to contact 4 is not less than 5 ohms, or the resistance from contact 1 to contacts 2 and 3 is not greater than 5000 ohms. The switch has failed.

  Repair: Replace the switch.

  Stop.

Test Step 7. CHECK IF THE DIAGNOSTIC CODE REMAINS

1. Inspect the contacts of the harness connectors and clean the harness connectors.

2. Reconnect all the 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 1521 FMI 03.

Expected Result:

The CID 1521 FMI 03 is active.

Results:

• YES - The CID 1521 FMI 03 is active. The diagnostic code has not been corrected. The ECM may have failed.

  Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic code is not found, replace the ECM. See Troubleshooting, "Electronic Control Module (ECM) - Replace".

  Stop.

• NO - The CID 1521 FMI 03 is not active. The diagnostic code does not exist at this time.

  Repair: The initial diagnostic code was probably caused by a poor electrical connection or a short at one of the harness connectors that was disconnected and reconnected. Resume normal machine operation.

  Stop.