GUARD A. 3D5397 - Caterpillar

Illustration 1 g01309283
Connections of the transmission oil temperature sensor
The diagnostic code is associated with the transmission oil temperature sensor. The FMI 04 means that the ECM has determined that the voltage of the circuit for the sensor is below normal.The possible causes for this diagnostic code are listed:
The sensor supply circuit to the transmission oil temperature sensor is shorted to ground.
A sensor has failed.
The Transmission 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 0177 FMI 04 is active before performing this procedure.Note: Use the digital multimeter for the measurements in this procedure.Test Step 1. CHECK THE SENSOR
Turn the disconnect switch and the key start switch to the ON position.
Ensure that the diagnostic code is active.
Observe the status of the diagnostic code. Disconnect the sensor from the machine harness. Expected Result:The CID 0177 FMI 04 remains active. The FMI has not changed and the "04" is still active.Results:
OK - The diagnostic code remains active. The sensor is correct. Proceed to Test Step 2.
NOT OK - The diagnostic code is no longer active. The sensor has failed.Repair: Replace the sensor.STOPTest Step 2. CHECK THE WIRING HARNESS OF THE SENSOR FOR A SHORT TO GROUND
Turn the key start switch and the disconnect switch to the OFF position.
Disconnect the machine harness from the sensor.
Disconnect the machine harness connector(s) from the ECM.
At the machine harness connector for the ECM, measure the resistance from the signal contact J2-25 (wire 428-OR(Orange)) of the machine harness to all possible sources of ground. Measure the resistance to all contacts of the machine harness connectors for the ECM. Expected Result:Each resistance measurement is greater than 5000 ohms.Results:
OK - Each resistance measurement is greater than 5000 ohms. The machine harness is correct. Proceed to Test Step 3.
NOT OK - One or more resistance measurements is not correct. There is a short in the machine harness. The short is between signal contact J2-25 (wire 428-OR(Orange)) and the circuit with the low resistance measurement. Repair the machine harness or replace the machine harness.STOPTest Step 3. CHECK IF THE DIAGNOSTIC CODE IS STILL ACTIVE.
Inspect the harness connectors. 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. Make sure that the connectors are fully seated and that the clips for each connector are completely fastened.
Turn the disconnect switch and the key start switch to the ON position.
Operate the machine.
Determine if the CID 0177 FMI 04 is active. Expected Result:The CID 0177 FMI 04 is active.Results:
YES - The CID 0177 FMI 04 is active. The problem has not been corrected.Repair: Check the circuit again. If the Caterpillar Electronic Technician (Cat ET) is available, use the