RING 1481202 - Caterpillar

Illustration 1 g01259614
Fuel Level Sensor connectionsThis diagnostic code is associated with the fuel level sensor. The FMI 03 diagnostic code is activated when the Machine Control ECM detects that voltage of the input signal from the fuel level sensor is above normal.The sensor is a PWM sensor that operates at a frequency of approximately 500 hertz. As the amount of fuel in the fuel tanks increases, the duty cycle signal from the sensor does not increase in a linear fashion. When little or no fuel is in the fuel tank, the PWM duty cycle input to the ECM is approximately 5%. When the fuel tank is half full of fuel, the duty cycle of the sensor will be approximately 30%. When the fuel tank is full of fuel, the PWM duty cycle input to the ECM is approximately 95%. The possible causes of this diagnostic code are listed:
The sensor power supply circuit is open.
The return circuit is open.
The signal circuit is open or the sensor is disconnected.
The signal circuit is shorted to the sensor power supply.
The sensor has failed.
The 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. Verify that the of CID 0096 FMI 03 diagnostic code is active before performing this procedure.Test Step 1. CHECK THE SUPPLY VOLTAGE AT THE SENSOR
Turn the key switch and the disconnect 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 supply contact A (wire 158-BR) and return contact B (wire J878-YL).
At the machine harness connector for the sensor, measure the voltage between supply contact A (wire 158-BR) and frame ground.Expected Result:Both voltage measurements between 18.0 VDC and 28.0 VDC.Results:
OK - Both voltage measurements are between 18.0 VDC and 28.0 VDC. The power supply circuit is correct. Proceed to Test Step 2.
NOT OK - One or both of the voltage measurements is less than 18.0 VDC. The power supply circuit is not correct.Repair: If both voltage measurements are less than 18.0 VDC, there is a problem with the power supply circuit for the sensor. Refer to the complete machine Electrical System Schematic. Verify that the 5 Amp Sensors Fuse is not open. Check all of the connections that are in the power supply circuit. Ensure that all connections are clean, secure and in good condition. Repair the machine harness