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| Illustration 1 | g01248848 |
Schematic of the Transmission Oil Temperature Sensor | |
This diagnostic trouble code is associated with the transmission oil temperature sensor. The FMI 01 means that the ECU has determined that the signal of the sensor is below the normal range.
The possible causes of this failure are listed below:
- The position sensor has failed.
- The signal circuit of the sensor is shorted to the ground.
- The sensor needs to be calibrated.
- The ECU has failed. This is unlikely.
Note: The following test procedure may create other diagnostic trouble codes. Ignore these created diagnostic trouble codes and clear the diagnostic trouble codes when the original diagnostic trouble code has been corrected.
Note: Use a digital multimeter for the measurements in this procedure.
Test Step 1. INSPECT THE SENSOR
- Perform a visual inspection of the sensor, the wiring for the sensor and the hardware that is associated with the sensor.
Expected Result:
There is no apparent damage to the sensor, the wiring for the sensor or the hardware that is associated with the sensor.
Results:
- OK - There is no apparent damage to the sensor, the wiring for the sensor or the hardware that is associated with the sensor. Proceed to Test Step 2.
- NOT OK - There is apparent damage to the sensor, the wiring for the sensor or the hardware that is associated with the sensor.
Repair: Replace the damaged part.
Proceed to Test Step 7.
Test Step 2. CHECK FOR POWER AT THE SENSOR
- Do not disconnect the harness connector from the sensor.
- At the back of the harness connector for the sensor, insert a multimeter probe along the voltage supply wire contact A.
- Turn the key start switch and the disconnect switch to the ON position.
- Measure the voltage from contact A to frame ground.
Expected Result:
The voltage is 8 volts.
Results:
- OK - The voltage is 8 volts. Proceed to Test Step 3.
- NOT OK - The voltage is not 8 volts. The circuit is open.
Repair: Repair the machine harness or replace the machine harness.
STOP
Test Step 3. CHECK FOR PROPER GROUND AT THE SENSOR
- The machine harness remains connected to the sensor.
- Turn the key start switch and the disconnect switch to the OFF position.
- Remove the multimeter probe from the voltage supply wire contact A.
- At the back of the harness connector for the sensor, insert a multimeter probe along the ground wire contact B.
- Measure the resistance from contact B to frame ground.
Expected Result:
The resistance is less than 5 ohms.
Results:
- OK - The resistance is less than 5 ohms. The ground circuit is correct. Proceed to Test Step 4.
- NOT OK - The resistance is greater than 5 ohms. The ground circuit in the machine harness has failed.
Repair: Replace the machine harness or repair the machine harness.
STOP
Test Step 4. CHECK THE SIGNAL OF THE SENSOR
- Turn the key start switch and the disconnect switch to the OFF position.
- At the back of the harness connector for the sensor, remove the multimeter probe from contact A and insert the probe along the signal wire contact C.
- At the back of the harness connector for the sensor, insert the multimeter probe along the ground wire contact B.
- Turn the disconnect switch and the key start switch to the ON position.
- Monitor the signal of the sensor with a digital multimeter.
- Without disconnecting the sensor or the hardware that is associated with the sensor from the machine, take the sensor through the full operating range of the sensor.
Note: On some machines, it may be necessary to start the engine in order to take the sensor through the full operating range of the sensor.
Expected Result:
The sensor's signal responds in the manner that is described at the beginning of this procedure. The CID 0177 FMI 01 is not active at the maximum range of the sensor.
Results:
- OK - The sensor's signal responds correctly. The sensor is operating correctly. Proceed to Test Step 5.
- NOT OK - The sensor's signal does not respond correctly. The sensor is NOT operating correctly.
Repair: Replace the sensor.
STOP
Test Step 5. CHECK THE SIGNAL AT THE ECU
- Turn the key start switch and the disconnect switch to the OFF position.
- Insert the multimeter probes into the back of the ECU connector along J2-25 (wire 428-OR) and J2-22 (wire J765-BU).
- Turn the disconnect switch and the key start switch to the ON position.
- Monitor the signal of the sensor with a digital multimeter.
- Without disconnecting the sensor or the hardware that is associated with the sensor from the machine, take the sensor through the full operating range of the sensor.
Note: On some machines, it may be necessary to start the engine in order to take the sensor through the full operating range of the sensor.
Expected Result:
The sensor's signal responds in the manner that is described at the beginning of this procedure. The CID 0177 FMI 01 is not active at the maximum range of the sensor.
Results:
- OK - The sensor's signal responds correctly. The sensor is operating correctly. Proceed to Test Step 6.
- NOT OK - The sensor's signal does not respond correctly. The harness has failed.
Repair: Repair the machine harness or replace the machine harness.
STOP
Test Step 6. CHECK THE SIGNAL CIRCUIT FOR A SHORT IN THE HARNESS
- The key start switch and the disconnect switch remain in the OFF position.
- Disconnect the machine harness connectors from the sensor and the ECU.
- Measure the resistance between contact J2-25 (wire 428-OR) and all contacts that are used in the machine harness connectors for the ECU.
Expected Result:
Each resistance measurement is greater than 5000 ohms.
Results:
- OK - Each of the resistance measurements are greater than 5000 ohms. The circuit is correct. Proceed to Test Step 7.
- NOT OK - The resistance is less than 5 ohms. The signal circuit is shorted to another circuit in the harness.
Repair: Repair the machine harness or replace the machine harness.
STOP
Test Step 7. CHECK THE ADJUSTMENT AND/OR THE CALIBRATION OF THE SENSOR
- Turn the disconnect switch and the key start switch to the ON position.
- Perform the adjustment procedure for the position sensor, if necessary.
- Without disconnecting the sensor or the hardware that is associated with the sensor, move the sensor through the entire range of motion.
Note: On some vehicles, it may be necessary to start the engine in order to move the sensor through the entire range of motion.
- Check the status of the diagnostic trouble code.
Expected Result:
The CID 0177 FMI 01 is not active.
Results:
- OK - The diagnostic is not active. The adjustment and/or the calibration has corrected the failure. Resume normal operation.STOP
- NOT OK - CID 0177 FMI 01 is still active.
Repair: Exit this procedure. Perform this procedure again.
STOP
Test Step 8. CHECK IF THE DIAGNOSTIC TROUBLE CODE REMAINS.
- Inspect the harness connectors and clean the contacts of the harness connectors and check the wires for damage to the insulation that is caused by excessive heat, battery acid, or chafing.
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the circuit.
- Reconnect all harness connectors making sure that the connectors are fully seated and the clips for each connector are completely fastened.
- Turn the disconnect switch and the key start switch to the ON position.
- Operate the machine.
- Check the status of the CID 0177 FMI 01.
Expected Result:
The CID 0177 FMI 01 is active.
Results:
- YES - The CID 0177 FMI 01 is active. The diagnostic trouble code has not been corrected.
Repair: Check the relay circuit again. Use the Caterpillar Electronic Technician (ET) service tool, if available, in order to perform a "Wiggle Test" on the machine wiring harness. The wiggle test can detect momentary or intermittent shorts or opens in the machine wiring harness. It is unlikely that the ECU has failed. Exit this procedure and perform this procedure again. If the cause of the diagnostic trouble code is not found, replace the ECU. Prior to replacing an ECM, always contact your dealership's Technical Communicator for possible consultation with Caterpillar. This consultation may greatly reduce repair time. See Testing and Adjusting, "Electronic Control Unit - Replace".
STOP
- NO - The CID 0177 FMI 01 is not active. The diagnostic trouble code does not exist at this time.
Repair: The initial diagnostic trouble code 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