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

Illustration 1	g00756724
Schematic of the Speed Sensor (Transmission Output 1)

This diagnostic code is recorded when the ECM receives an incorrect signal from the speed sensor. The signal is below the dropout signal level. The engine must be running. The incorrect signal that is being read by the ECM has the following characteristics: erratic, intermittent and incorrect. The ECM can determine that a problem exists by comparing the signal data. The ECM compares the two signals from the speed sensors. The ECM checks if one of the two signals is invalid or out of range.

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

• The signal from the transmission output speed sensor (No. 1) to the ECM is incorrect.

• The ECM is NOT receiving the correct information about the transmission output speed sensor (No. 1) 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 09. Correct the related CID 0248 FMI 09 first. Then view the status of the other diagnostic codes and correct the other active codes.

Test Step 1. CHECK THE SENSOR RESISTANCE.

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 1000 ohms and 1200 ohms.

Results:

• OK - The speed sensor has not failed. Proceed to test step 2.

• NOT OK - The speed sensor has failed.

  Repair: Replace the sensor. Adjust the speed sensor properly during the installation. See Testing and Adjusting, "Speed Sensor - Adjust".

  Stop.

Test Step 2. CHECK THE SIGNAL CIRCUIT FOR AN OPEN IN THE MACHINE HARNESS.

1. Place a jumper between the two contacts of the machine harness connector for the speed sensor.

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

3. Measure the resistance from the sensor signal J1-65 wire (E900-WH) to the return contact J1-63 wire (E901-GN) of the machine harness.

Expected Result:

There should be continuity (less than 5.0 ohms resistance).

Results:

• OK - The signal circuit in the machine harness is correct. Proceed to test step 3.

• NOT OK - There is an open in the signal circuit of the machine harness.

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

  Stop.

Test Step 3. CHECK THE SIGNAL FOR A SHORT.

1. Remove the jumper between the two contacts of the speed sensor of the previous test "CHECK SIGNAL CIRCUIT FOR AN OPEN IN THE MACHINE HARNESS".

2. Reconnect the machine harness to the speed sensor.

3. At the J1 and J2 harness connectors, measure the resistance between J1-65 (wire E900-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 - The machine harness is correct. Proceed to test step 4.

• NOT OK - There is a short in the machine harness.

  Repair: The short is between the signal circuit (wire E900-WH) and the circuit with the low resistance measurement. Repair the machine harness or replace the machine harness.

  Stop.

Test Step 4. CHECK IF THE DIAGNOSTIC CODE REMAINS.

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. Start the engine. Place the machine in first gear and move the machine.

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 NOT active. The diagnostic code does not exist at this time. The initial diagnostic code was probably caused by a poor electrical connection or a short in one of the wires in the machine harness. Resume normal machine operation. Stop.

• NO - The diagnostic code remains active. Proceed to test step 5.

Test Step 5. CHECK THE ADJUSTMENT OF THE SENSOR.

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

2. Perform the instructions for the previous test "CHECK IF DIAGNOSTIC CODE REMAINS" again.

Expected Result:

The CID 0585 FMI 02 is NO longer active.

Results:

• YES - The diagnostic code is NO longer active. Adjustment of the speed sensor corrected the diagnostic code. Stop.

• NO - The diagnostic code remains present.

  Repair: Replace the speed sensor.

  If conditions are not resolved, proceed to test step 6.

Test Step 6. CHECK IF THE DIAGNOSTIC CODE REMAINS.

1. Remove connectors J1 and J2 from the ECM. Inspect the contacts of the harness connectors and 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. Check the status of the CID 0585 FMI 02. The diagnostic code is active or the diagnostic code is NOT active.

Expected Result:

The CID 0585 FMI 02 is NOT active.

Results:

• YES - The diagnostic code is NOT present. The diagnostic code does not exist at this time. The new speed sensor corrected the diagnostic code. Resume normal machine operation. Stop.

• NO - The diagnostic code has not been corrected.

  Repair: It is unlikely that the ECM has failed. Perform CID 0585 FMI 02 again. If the cause of the diagnostic code is not found, replace the ECM. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  Stop.