GEAR-HYDRAULIC PUMP DRIVE 7N9321 - Caterpillar

Illustration 1 g00738273
Schematic of the temperature sensor (Rear axle oil)
This diagnostic code is associated with the temperature sensor (Rear axle oil). The FMI 03 means that the ECM has determined that the voltage of the circuit for the sensor is above normal.The pressure sensors are PWM sensors. The PWM signal is based on the input pressure and the signal will vary. The possible causes of this diagnostic code are listed below:
The sensor signal circuit in the machine harness is open.
The signal circuit for the sensor is shorted to the +battery circuit.
The sensor has failed.
The power circuit or the ground circuit has failed.
Failure of the ECM 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 0428 FMI 03 is active before performing this procedure.Note: Use the 146-4080 Digital Multimeter for the measurements in this procedure.Test Step 1. CHECK FOR POWER AT THE SENSOR.
Do not disconnect the harness connector from the sensor.
Turn the key start switch and the disconnect switch to the ON position.
At the back of the harness connector for the sensor, insert a 7X-1710 Multimeter Probe along the voltage supply wire (contact A).
Measure the voltage from the supply to frame ground. Expected Result:The voltage is 8 DCV.Results:
OK - The voltage is 8 DCV. Proceed to Test Step 2.
NOT OK - The voltage is not 8 DCV. The + battery circuit in the machine harness has failed.Repair: Replace the machine harness or repair the machine harness.STOPTest Step 2. 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 7X-1710 Multimeter Probe from the voltage supply wire (contact A).
At the back of the harness connector for the sensor, insert a 7X-1710 Multimeter Probe along the ground wire (contact B).
Measure the resistance from ground wire 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 3.
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.STOPTest Step 3. CHECK THE WIRING HARNESS OF THE SENSOR FOR AN OPEN CIRCUIT.
The key start switch and the disconnect switch remain in the OFF position.
Disconnect the machine harness from the sensor.
At the harness connector for the sensor, connect a jumper wire between contact B and contact C.
Disconnect the machine harness connectors from the ECM.
At the harness connector for the ECM, measure the resistance between contact 17 (wire 446-PU(Purple)) and frame ground (wire 201-BK(Black)). Expected Result:The resistance measurement is less than 5 ohms.Results:
OK - The resistance measurement is less than 5 ohms. The circuit is correct. Proceed to Test Step 4.
NOT OK - The resistance is greater than 5 ohms. The circuit is not