GEAR-PLANETARY 8E7937 - Caterpillar

Illustration 1 g03366435
Transmission Oil Temperature sensor connections
This diagnostic code is associated with the transmission oil temperature sensor. The FMI 03 diagnostic code means that the Transmission ECM has detected that the voltage of the sensor circuit is above 4.9 VDC and the resistance of the sensor is more than 33650 ohms.In addition to monitoring the voltage of the sensor signal, the ECM monitors the resistance of the sensor signal. The ECM associates the resistance value of the sensor circuit with a specific temperature of the transmission oil.The resistance range of the sensor that the ECM will consider valid is 33650 ohms at −40 °C (−40.0 °F) to 18.6 ohms at 150 °C (302.0 °F).Conditions that can cause this diagnostic code to be activated are listed below:
The sensor has failed.
The ground circuit for the sensor is open in the machine harness.
The signal circuit in the machine harness is open or the sensor is disconnected.
The ECM has failed. This situation is unlikely.
The oil temperature is below −40 °C (−40.0 °F).Test Step 1. CHECK THE RESISTANCE OF THE SENSOR
Turn the disconnect switch and the key start switch to the OFF position.
Disconnect the machine harness connector from the sensor.
At the connector for the sensor, measure the resistance between contact 1 and contact 2. Expected Result:The resistance measurement is less than 33650 ohms.Results:
OK - The resistance measurement is less than 33650 ohms. The resistance of the sensor is correct. Proceed to Test Step 2.
NOT OK - The resistance measurement is greater than 33650 ohms. The transmission oil temperature sensor has failed.Repair: Replace the transmission oil temperature sensor. Ensure that the new sensor corrects the problem.STOPTest Step 2. CHECK THE GROUND CIRCUIT OF THE HARNESSThe sensor remains disconnected from the machine harness. The disconnect switch and the key start switch remain in the OFF position.
Disconnect the J1 machine harness connector from the ECM.
At the machine harness connector for the sensor, measure the resistance between contact 2 (wire 202-BK(Black)) to frame ground. Expected Result:The resistance measurement is less than 5 ohms.Results:
OK - The resistance measurement is less than 5.0 ohms. The ground circuit is correct. Proceed to Test Step 3.
NOT OK - The resistance measurement is greater than 5.0 ohms. There is an open circuit or a bad connection in the ground circuit for the sensor.Repair: A resistance measurement that is greater than 5000 ohms could indicate that a wire is either not connected or a wire is open. A resistance measurement that is greater than 5 ohms but less than 5000 ohms could indicate that one of the connection points or a splice connection in the circuit is not open but is not a good connection.Refer to the complete Electrical System Schematic of the machine. Ensure that all connections and splices in the ground circuit for the sensor are clean, secure and in good condition.Start at the component connector for the defective circuit. While checking the wire for an open or a bad connection point, work your way through the circuit in order to isolate