IT38H Integrated Toolcarrier and 938H Wheel Loader Transmission Electronic Control System Caterpillar

Illustration 1	g01448264
Schematic of the Transmission Direction Switch

This diagnostic code is associated with the Transmission Direction Switch. The Transmission Direction 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 all of the switch inputs are in the open state at the same time.

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 0623 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 J1-70 (wire C216-BK) of the machine harness for the ECM and the frame ground.

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 5 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 8-pin connector for the switch from the machine harness.

4. At the machine harness connector for the ECM, measure the resistance from contact J2-23 (wire G763-PU), contact J2-28 (wire G755-GY), and contact J2-49 (wire G750-BU) 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:

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

• NO - One or more of the measurements is less than 5000 ohms. There is a short in the machine harness.

  Repair: The short is between wire G763-PU and the circuit with the lowest resistance measurement, wire G755-GY and the circuit with the lowest resistance measurement, or the short is between wire G750-BU 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 3 (wire G750-BU) and contact 2 (wire G763-PU).

3. At the harness connector for the ECM, measure the resistance from contact J2-23 (wire G763-PU) to contact J2-49 (wire G750-BU).

4. At the harness connector for the switch, connect a jumper wire between contact 2 (wire G763-PU) and contact 3 (wire G755-GY).

5. At the harness connector for the ECM, measure the resistance from contact J2-28 (wire G755-GY) to contact J2-23 (wire G763-PU).

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 5 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 (NEUTRAL 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 neutral position.

4. Connect one lead from a multimeter to contact 1 (wire C216-BK) of the harness connector for the switch.

5. Connect the other lead from a multimeter to contact 3 (wire G755-GY) of the harness connector for the switch.

6. Measure the resistance between contact 1 (wire C216-BK) and contact 3 (wire G755-GY). Note the resistance.

7. Disconnect the lead from contact 3 (wire G755-GY) and connect the lead to contact 2 (wire G763-PU).

8. Measure the resistance between contact 1 (wire C216-BK) and contact 2 (wire G763-PU).

9. Disconnect the lead from contact 2 (wire G763-PU) and connect the lead to contact 4 (wire G750-BU).

10. Measure the resistance between contact 1 (wire C216-BK) and contact 4 (wire G750-BU).

Expected Result:

The resistance from contact 3 to contact 1 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 3 to contact 1 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 neutral position. Proceed to Test Step 5.

• NO - The resistance from contact 3 to contact 1 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 5. CHECK THE OPERATION OF THE SWITCH (FORWARD POSITION)

1. Rotate the switch to the forward position.

2. Connect one lead from a multimeter to contact 3 (wire G755-GY) of the harness connector for the switch.

3. Connect the other lead from a multimeter to contact 1 (wire C216-BK) of the harness connector for the switch.

4. Measure the resistance between contact 3 (wire G755-GY) and contact 1 (wire C216-BK). Note the resistance.

5. Disconnect the lead from contact 3 (wire G755-GY) and connect the lead to contact 2 (wire G763-PU).

6. Measure the resistance between contact 1 (wire C216-BK) and contact 2 (wire G763-PU).

7. Disconnect the lead from contact 2 (wire G763-PU) and connect the lead to contact 4 (wire G750-BU).

8. Measure the resistance between contact 1 (wire C216-BK) and contact 4 (wire G750-BU).

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 forward position. Proceed to Test Step 6.

• 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 6. CHECK THE OPERATION OF THE SWITCH (REVERSE POSITION)

1. Rotate the switch to the reverse position.

2. Connect one lead from a multimeter to contact 1 (wire C216-BK) of the harness connector for the switch.

3. Connect the other lead from a multimeter to contact 3 (wire G755-GY) of the harness connector for the switch.

4. Measure the resistance between contact 1 (wire C216-BK) and contact 3 (wire G755-GY). Note the resistance.

5. Disconnect the lead from contact 3 (wire G755-GY) and connect the lead to contact 2 (wire G763-PU).

6. Measure the resistance between contact 1 (wire C216-BK) and contact 2 (wire G763-PU).

7. Disconnect the lead from contact 2 (wire G763-PU) and connect the lead to contact 4 (wire G750-BU).

8. Measure the resistance between contact 1 (wire C216-BK) and contact 4 (wire G750-BU).

Expected Result:

The resistance from contact 1 to contact 4 is less than 5 ohms, and the resistance from contact 1 to contacts 3 and 2 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 3 and 2 is greater than 5000 ohms. The switch is operating correctly in the reverse 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 3 and 2 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 0623 FMI 03.

Expected Result:

The CID 0623 FMI 03 is active.

Results:

• YES - The CID 0623 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 Testing And Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP

• NO - The CID 0623 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