725, 730, 735, 740 and 740 EJECTOR Articulated Trucks Power Train Electronic Control System Caterpillar

Illustration 1	g00756227
Schematic of the Speed Sensor (Engine)

This diagnostic code is recorded when the ECM reads the signal from the sensor and the ECM determines that the signal is erratic, intermittent or incorrect. This is determined when the ECM compares the signal from the engine speed sensor to the signal from the torque converter output speed sensor. A diagnostic code is recorded when the signal from the engine speed sensor is below the dropout value and the engine speed is above low idle. This problem prevents the ECM from calculating the ratio of the torque converter.

Note: The engine must be running. The engine speed signal must be received from the torque converter output speed sensor in order for the ECM to display this diagnostic code as being present.

One of the following conditions must be present before the diagnostic code will be active:

• The signal from the engine speed sensor to the transmission ECM is incorrect.

• The transmission ECM is NOT receiving the correct information about the engine speed sensor over the data link.

Note: Check for other related diagnostic codes before performing the following diagnostic code procedure. Check for an active CID 0248 FMI 12. Correct the related CID 0248 FMI 12 first. Then view the status of the other diagnostic codes and correct the other active codes.

Test Step 1. CHECK THE RESISTANCE OF THE SENSOR.

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

2. Disconnect the machine harness from the speed sensor.

3. At the connector for the speed sensor, measure the resistance between the two contacts of the connector of the speed sensor.

Expected Result:

The resistance measurement is between 110 ohms and 200 ohms.

Results:

• OK - The resistance measurement is between 110 ohms and 200 ohms. The speed sensor has not failed. Proceed to Test Step 2.

• NOT OK - The speed sensor has failed.

  Repair: The speed sensor has failed. Replace the sensor. Adjust the speed sensor properly when the sensor is being installed. See Testing and Adjusting, "Speed Sensor - Adjust". Verify that the new sensor corrects the problem.

  Stop.

Test Step 2. CHECK THE RETURN CIRCUIT.

1. The machine harness remains disconnected from the sensor.

2. Turn the key start switch to the OFF position.

3. At the machine harness connector for the sensor, measure the resistance between contact 2 (E963-BK) and frame ground.

Expected Result:

The resistance should measure 20 ohms or less.

Results:

• OK - The resistance measures 20 ohms or less. The return circuit is correct. Proceed to Test Step 3.

• NOT OK - The resistance does not measure 20 ohms or less.

  Repair: The return circuit (E963-BK) in the machine harness has excessive resistance (open). Repair the machine harness or replace the machine harness.

  Stop.

Test Step 3. CHECK THE SIGNAL CIRCUIT FOR AN OPEN IN THE MACHINE HARNESS.

1. At the machine harness connector for the speed sensor, place a jumper between the two contacts.

2. Disconnect the machine harness connectors J1 and J2 from the ECM.

3. At the machine harness connectors J1 and J2, measure the resistance from J1-40 (sensor signal) to J1-41 (the return circuit).

Expected Result:

There should be less than 5.0 ohms resistance.

Results:

• OK - There is less than 5.0 ohms resistance. The signal circuit in the machine harness is correct. Proceed to Test Step 4.

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

  Repair: The signal circuit (E964-WH) is open in the machine harness. Repair the machine harness or replace the machine harness.

  Stop.

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

1. If a jumper was used in a previous step, remove the jumper.

2. Reconnect the machine harness to the speed sensor.

3. At the harness connector J1 and harness connector J2, measure the resistance between J1-40 (E964-WH) and all sources of positive voltage and ground. The possible sources of positive voltage are contacts: 725 and 730 machines J1-11, J1-58, J2-1, J2-15, J2-16, J2-17, J2-23, J2-25, J1-39, J2-40, J2-44, J2-45, J2-47, J2-51, J2-57, J2-58, J2-60, J2-62, J2-63, J2-64, J2-65, J2-68 and J2-70. 735 machines J1-11, J1-58, J2-1, J2-14, J2-15, J2-16, J2-17, J2-23, J2-25, J1-39, J2-40, J2-44, J2-45, J2-47, J2-51, J2-57, J2-58, J2-60, J2-61, J2-62, J2-63, J2-64, J2-65, J2-68 and J2-70. 740 machines J1-11, J1-58, J2-1, J2-14, J2-15, J2-16, J2-17, J2-23, J2-25, J1-39, J2-40, J2-44, J2-45, J2-47, J2-55, J2-57, J2-58, J2-60, J2-68 and J2-70. The possible sources of ground are contacts: 725 and 730 machines J1-12, J2-2, J2-12, J2-13, J2-22, J2-36, J2-41, J2-46, J2-49, J2-52, J2-56, J2-59, J2-69 and frame ground. 735 machines J1-12, J1-20, J2-2, J2-12, J2-13, J2-18, J2-22, J2-36, J2-46, J2-49, J2-52, J2-56, J2-59 and J2-69. 740 machines J1-12, J1-20, J2-2, J2-12, J2-13, J2-22, J2-36, J2-46, J2-56, J2-59 and J2-69.

Expected Result:

Each resistance should be greater than 5000 ohms.

Results:

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

• NOT OK - Each resistance is not greater than 5000 ohms.

  Repair: There is a short in the machine harness. The short is between the signal circuit (E964-WH) and the circuit that has a low resistance measurement. Repair the machine harness or replace the machine harness.

  Stop.

Test Step 5. CHECK IF THE DIAGNOSTIC CODE IS STILL ACTIVE.

1. Clean the contacts of the harness connectors.

2. Reconnect all harness connectors.

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

4. Start the engine and run the engine at low idle.

5. View the status of the diagnostic code. The diagnostic code is active or the diagnostic code is NOT active.

Expected Result:

The diagnostic code is NO longer active.

Results:

• YES - The diagnostic code is NO longer active. Proceed to Test Step 6.

• NO - The diagnostic code indicator does not show "SERV CODE".

  Repair: The diagnostic code is NOT present. 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 ADJUSTMENT OF THE SENSOR.

1. Check the adjustment of the speed sensor. See Testing and Adjusting, "Speed Sensor - Adjust".

2. Clean the contacts of the harness connectors.

3. Reconnect all harness connectors.

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

5. Start the engine and run the engine at low idle.

6. Enter service mode of the Caterpillar Monitoring System. Put the CID 0190 FMI 02 diagnostic code on hold.

7. Observe the status of the diagnostic code indicator.

Expected Result:

The diagnostic code indicator shows "SERV CODE".

Results:

• YES - The diagnostic code indicator shows "SERV CODE".

  Repair: Replace the speed sensor.

  Proceed to Test Step 7.

• NO - The diagnostic code indicator does not show "SERV CODE".

  Repair: The diagnostic code is NOT present. Adjustment of the speed sensor corrected the failure.

  Stop.

Test Step 7. CHECK IF THE DIAGNOSTIC CODE IS STILL ACTIVE.

1. Remove connector J1 and connector J2 from the ECM. Inspect the contacts and clean the contacts of the harness connectors.

2. Reconnect all harness connectors.

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

4. Enter service mode of the Caterpillar Monitoring System. Put the CID 0190 FMI 02 diagnostic code on hold.

5. Operate the machine.

6. Determine if CID 0190 FMI 02 is present.

Expected Result:

CID 0190 FMI 02 is present.

Results:

• YES - CID 0190 FMI 02 is 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 power train ECM. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  Stop.

• NO - CID 0190 FMI 02 is not present.

  Repair: The problem does not exist at this time. The new speed sensor corrected the problem. Resume normal machine operation.

  Stop.