D3G, D4G and D5G Track-Type Tractors Electrohydraulic Power Train Systems Caterpillar

As the operator presses the buttons for the accelerate/decelerate, the speed display does not respond properly.

The possible causes of this failure are listed below:

• The voltage supply J1-13 (wire 709-OR) to the display is open.

• The return circuit J1-9 (wire F750-YL) is open.

• The signal circuit J2-33 (wire 899-BU) is shorted to the + battery.

• The signal circuit J2-33 (wire 899-BU) is open or the speed display is disconnected.

• The speed display has failed.

• The ECM has failed. This is unlikely.

Test Step 1. CHECK THE SUPPLY CIRCUIT FOR THE SPEED DISPLAY AT THE ECM.

1. Place the disconnect switch and the key start switch in the ON position.

2. DO NOT DISCONNECT the machine harness from the ECM. At J1 and J2 connectors of the ECM, prepare to make a voltage measurement by using the 7X-1710 Multimeter Probe .

3. At the machine harness for the ECM, insert the probe into the back of connectors J1 and J2. Measure the voltage (VDC) between J1-13 (10 volt supply) and J1-9 (10 volt return). Make a note of the measurement.

4. Measure the voltage at the speed display. Measure the voltage between wire (709-OR) and wire (F750-YL). Make a note of the measurement.

Expected Result:

The voltage measures approximately 10 VDC.

Results:

• OK - The voltage measures approximately 10 VDC. The speed display has failed.

  Repair: Replace the speed display gauge.

  STOP

• NOT OK - The voltage does NOT measure approximately 10 VDC. The supply circuit is shorted or the ECM has failed. Proceed to Test Step 2.

Test Step 2. CHECK THE SUPPLY CIRCUIT FOR A SHORT.

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

2. Disconnect wire (709-OR) from the speed display.

3. Disconnect the J1 and J2 machine harness from the ECM.

4. At machine harness connector J1-13, measure the resistance to all other J1 and J2 contacts.

Expected Result:

The resistance should be greater than 5000 ohms for each measurement.

Results:

• OK - The resistance is greater than 5000 ohms for each measurement. The machine harness is correct. Proceed to Test Step 5.

• NOT OK - The resistance is not greater than 5000 ohms for each measurement.

  Repair: There is a short in the machine harness. The short is between the circuit with the low resistance measurement and wire 709-OR. Repair the machine harness or replace the machine harness.

  STOP

Test Step 3. CHECK THE SIGNAL CIRCUIT FOR AN OPEN.

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

2. At the speed display gauge, place a jumper from J2-33 (wire 899-BU) to J1-13 (wire 709-OR).

3. The J1 and J2 machine harness remains disconnected from the ECM.

4. At the machine harness connector for the ECM, measure the resistance. Measure the resistance from contact J2-33 to contact J1-13.

Expected Result:

The resistance measurement should be less than 5.0 ohms.

Results:

• OK - The resistance measurement is less than 5.0 ohms. The machine harness is correct. Proceed to Test Step 4.

• NOT OK - The resistance measurement is not less than 5.0 ohms.

  Repair: There is an open circuit in the machine harness. The open is in wire 899-BU or wire 709-OR of the machine harness. Repair the machine harness or replace the machine harness.

  STOP

Test Step 4. CHECK THE SIGNAL CIRCUIT FOR A SHORT.

1. The key start switch and the disconnect switch remains OFF.

2. Remove the jumper from the speed display gauge.

3. The machine harness (J1 and J2) remains disconnected from the ECM.

4. At machine harness connectors, measure the resistance from contact J2-33 (signal) to all other contacts of J1 and J2.

Expected Result:

The resistance should be greater than 5000 ohms for each measurement.

Results:

• OK - The resistance is greater than 5000 ohms for each measurement. The machine harness is correct. Proceed to Test Step 5.

• NOT OK - The resistance is not greater than 5000 ohms for each measurement.

  Repair: There is a short in the machine harness. The short is between the circuit with the low resistance measurement and wire 899-BU. Repair the machine harness or replace the machine harness.

  STOP

Test Step 5. CHECK IF THE FAILURE IS STILL PRESENT.

1. Clean the contacts of the 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. Determine if the problem remains.

Expected Result:

The speed display is NOT operating properly.

Results:

• YES - The speed display is NOT operating properly. Proceed to Test Step 6.

• NO - The speed display is operating properly.

  Repair: The problem does not exist at this time. The initial problem 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

Test Step 6. CHECK THE PARAMETER SETTING.

1. Use the Caterpillar Electronic Technician and enter the screen for Status Group 5. See Troubleshooting, "Using Caterpillar Electronic to Determine Diagnostic Codes".

2. View the parameter for the Current Maximum Speed Setting. Compare the value for the parameter and the value that is on the speed display.

3. Press and hold the speed down button. The parameter setting on the ET should read approximately 0.217 and the speed display should display the minimum position.

4. Press and hold the speed up button. The parameter setting on the ET should read approximately 1.0 to 1.35 and the speed display will display 2.25 to 3.

   Note: The value for the speed display can vary. The variation will depend on the programmed value that was entered with the ET.

Expected Result:

The Current Maximum Speed Setting and the speed display change to the correct values.

Results:

• OK - The Current Maximum Speed Setting and the speed display change to the correct values. The indicator is working correctly.STOP

• NOT OK - The Current Maximum Speed Setting is correct, but the speed display does NOT have the correct value.

  Repair: Replace the speed display.

  STOP

• NOT OK - The Current Maximum Speed Setting does NOT change correctly. Verify that no other diagnostic codes are present.

  Repair: The problem has not been corrected. It is unlikely that the ECM has failed. Perform the previous Steps again. If the cause of the diagnostic code is not found, replace the ECM. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP