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

Illustration 1	g00582838
(1) Transmission output speed sensor (No. 1 and No. 2).

The transmission output speed sensor (No. 1) and the transmission output speed sensor (No. 2) are located behind an access cover at the rear of the differential housing.

Illustration 2	g01447867
Schematic of the Speed Sensor (No. 1) (Transmission Output)

This diagnostic code is associated with the Speed Sensor (No. 1) (Transmission Output). The FMI 08 means that the ECM has determined that the signal frequency or the signal pulse width is not within the expected range.

The possible causes of this diagnostic code are listed below:

• The sensor has failed.

• Intermittent connections or poor connections

• Mechanical devices are loose.

• The ECM has failed. This is unlikely.

Note: The following test procedure may create other diagnostic codes. Ignore these created diagnostic codes and clear the diagnostic codes when the original diagnostic code has been corrected. Ensure that the diagnostic code of CID 0585 FMI 08 is active before performing this procedure. The engine must be running in order for the diagnostic code to be active.

Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.

Test Step 1. CHECK THE SENSOR.

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

2. Ensure that the diagnostic code is active.

3. Disconnect the sensor from the machine harness.

Expected Result:

The diagnostic code is NO longer active.

Results:

• OK - The diagnostic code is NO longer active. The sensor has failed.

  Repair: Replace the sensor. Verify that the new sensor corrected this diagnostic code. The diagnostic code should NOT be active.

  STOP

• NOT OK - The diagnostic code remains active. The sensor is not the cause of the diagnostic code. Proceed to Test Step 2.

Test Step 2. CHECK FOR A SHORT IN THE HARNESS.

1. The sensor remains disconnected from the machine harness.

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

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

4. At the J1 machine harness connector for the ECM, measure the resistance between the signal contact J1-2 (wire E900-CF25-WH-18) to all other J1 and J2 contacts.

Expected Result:

Each resistance measurement should be greater than 5000 ohms.

Results:

• OK - The resistance that is measured is greater than 5000 ohms for each measurement. The harness is correct. The ECM may have failed.

  Repair: It is unlikely that the ECM has failed. Exit this procedure and perform this diagnostic code procedure again. If the cause of the diagnostic code is not found, replace the transmission ECM. See Testing and Adjusting, "Electronic Control Module (ECM) - Replace".

  STOP

• NOT OK - The resistance that is measured is NOT greater than 5000 ohms for each measurement. The machine harness has failed.

  Repair: There is a short in the machine harness. The short is between the signal circuit (wire E900-CF25-WH-18) and the circuit with the low resistance measurement. Repair the machine harness or replace the machine harness.

  STOP