24H Motor Grader Transmission Electronic Control System And Hydraulic Calibrations Caterpillar

Illustration 1	g00529248
Schematic For The Torque Converter Output Speed Sensor

This fault is recorded when the ECM reads the signal from the torque converter output speed sensor and the ECM determines that the signal is erratic, intermittent or incorrect. The ECM determines the condition by comparing the sensor signal to the torque converter output speed signal from the CAT Data Link.

Note: The status of the circuit is also shown when the display is in the "Other Status" mode. The other status mode is mode 3 of the Caterpillar Monitoring System. See Service Manual, SENR6717, "Caterpillar Monitoring System".

Service Notes: The engine must be running before the ECM will illuminate the fault present indicator. Ensure that the CID 672 FMI 02 fault is on hold.

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. Measure the resistance between the two contacts of the speed sensor's harness connector (wire L910-PK) and wire L911-YL).

      Expected Result: The resistance should be between 100 and 500 Ohms.

      Results:

      • OK - The speed sensor is not faulty. Proceed to Step 2.

      • NOT OK - The speed sensor has failed. Replace the sensor. Adjust the speed sensor properly when you install the sensor. Refer to Testing and Adjusting, "Speed Sensor - Adjust". STOP.

2. CHECK FOR A SHORTED HARNESS.

   The machine harness remains disconnected from the sensor.

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

   2. Disconnect machine harness connector J2 from the ECM.

   3. At the machine harness connector for the ECM, measure the resistance between contact J2-14 (wire L910-PK) and contact J2-20 (wire L911-YL).

      Expected Result: The resistance should be greater than 5000 ohms.

      Results:

      • OK - The resistance is greater than 5000 ohms. The return circuit is correct. Proceed to Step 3.

      • NOT OK - The resistance is less than 5000 ohms. Wire L910-PK is faulty or wire L911-YL is faulty. Repair the machine harness or replace the machine harness. STOP.

3. CHECK THE HARNESS (CONTINUED).

   1. The disconnect switch remains OFF. The speed sensor remains disconnected from the machine harness. Connector J2 remains disconnected from the ECM.

   2. At the machine harness connectors for the speed sensor, measure the resistance between wire L911-YL and frame ground. Also, measure the resistance between wire L910-PK and frame ground.

      Expected Result: The resistance is greater than 5000 ohms.

      Results:

      • OK - The resistance is greater than 5000 ohms. The signal circuit in the machine harness is correct. Proceed to Step 4.

      • NOT OK - The resistance is less than 5000 ohms. Wire L911-YL or wire L910-PK is shorted. Repair the machine harness or replace the machine harness. .

4. CHECK FOR AN OPEN HARNESS.

   The conditions of the previous step remain intact.

   1. At the machine harness connector for the speed sensor, place a jumper from contact 1 (wire L911-YL) to contact 2 (wire L910-PK).

   2. At the harness connectors, measure the resistance between J2-20 (wire L910-PK) and frame ground.

      Expected Result: The resistance should be less than 5 ohms.

      Results:

      • OK - The resistance is less than 5 ohms. The machine harness is correct. Proceed to Step 5.

      • NOT OK - The resistance is greater than 5 ohms. The machine harness is faulty. Wire L910-PK or L911-YL is open between the speed sensor and the ECM. Repair the machine harness or replace the machine harness.

5. CHECK IF THE FAULT 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. Start the engine and run the engine at low idle.

   5. Enter the service mode of the Caterpillar Monitoring System. Put the CID 0672 FMI 02 service code on hold.

   6. Observe the status of the fault present indicator. (Check whether "SERV CODE" is shown.)

      Expected Result: The fault present indicator shows "SERV CODE".

      Results:

      • YES - The fault remains present. Perform this procedure again. If the fault still remains present, replace the speed sensor. If the cause of the fault is still not found, replace the ECM. See Testing And Adjusting, "Electronic Control Module (ECM) - Replace"

      • NO - The fault is not present. The fault does not exist at this time. The initial fault was probably caused by a poor electrical connection or short at one of the harness connectors that was reconnected. Resume normal machine operation. STOP.