HEATER AS 1079652 - Caterpillar

Illustration 1 g01354594
Schematic of the transmission oil temperature sensor
This diagnostic code is associated with the transmission oil temperature sensor. "FMI 03" means that the Power Train/Chassis Electronic Control Module (ECM) has determined that the voltage of the circuit for the sensor is above normal.The transmission oil temperature sensor is a Pulse Width Modulated (PWM) sensor that operates at a frequency of approximately 500 Hz.The possible causes of this diagnostic code are listed below:
An open circuit.
A shorted harness.
A failed sensor.
The ECM may have failed. ECM failure 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 03" is active before performing this procedure.Test Step 1. CHECK THE SUPPLY VOLTAGE AT THE SENSOR.
Turn the battery disconnect switch and the key start switch to the ON position.
Check the voltage at the machine harness connector of the sensor from contact A (wire R800-OR(Orange)) to contact B (wire R998-BR(Brown)). Do not disconnect the sensor. Use the 7X-1710 Multimeter Probe to measure the voltage. Expected Result:The voltage should measure approximately 8 VDC.Results:
YES - The voltage is approximately 8 VDC. The voltage is correct. Proceed to Test Step 3.
NO - The voltage is not approximately 8 VDC. There is an open in the machine harness or the ECM has failed. Failure of the ECM is unlikely. Proceed to Test Step 2.Test Step 2. CHECK FOR AN OPEN IN THE SUPPLY CIRCUIT.
The key start switch and the battery disconnect switch remain in the ON position.
Disconnect the sensor from the machine harness.
At the machine harness connector for the sensor, measure the voltage from contact A (wire R800-OR(Orange)) to frame ground. Expected Result:The voltage should measure approximately 8 VDC. Results:
YES - The voltage measures approximately 8 VDC. The return circuit is open. Repair the machine harness or replace the machine harness. STOP.
NO - The voltage does not measure approximately 8 VDC. The supply circuit is open. Repair the machine harness or replace the machine harness.STOPTest Step 3. CHECK THE SIGNAL CIRCUIT.
Turn the battery disconnect switch and the key start switch to the ON position.
Disconnect the machine harness connector from the sensor.
At the machine harness connector for the sensor, measure the voltage between contact C (wire 428-OR(Orange)) and contact B (wire R998-BR(Brown)). Expected Result:The voltage should measure approximately 5 VDC. Results:
YES - The voltage is approximately 5 VDC. The voltage is correct. Replace the sensor.STOP
NO - The voltage is not approximately 5 VDC. The voltage is not correct. Proceed to Test Step 4.Test Step 4. CHECK FOR AN OPEN SIGNAL CIRCUIT.
Turn the key start switch and the battery disconnect switch to the OFF position.
The sensor remains disconnected from the machine harness.
Disconnect the machine harness from the ECM.
Place a jumper wire between contact C (wire 428-OR(Orange)) and contact B (wire R998-BR(Brown)) of the machine harness connector for the sensor.
At the machine harness connector of the ECM, measure the resistance between the signal